Prototype device of single-detector spectrometer, preparation method of prototype device, detector and application of prototype device

Abstract

The invention provides a prototype device of a single-detector spectrometer, a preparation method of the prototype device, a detector and application. The prototype device comprises a substrate, a p-type metal electrode, a p-type buffer layer, a p-type electron barrier layer, an n-type component gradient layer, an n-type contact layer, an n-type metal electrode and a passivation layer which are sequentially arranged from bottom to top. The PN junction with the gradually-changed band gap based on the material has the characteristic of adjustable bias voltage band gap, response of different wavelengths is achieved under different bias voltages, and analysis of spectrum signals ranging from 1500 nm to 2100 nm can be achieved in cooperation with a spectrum reconstruction algorithm. A single-detector micro spectrometer is manufactured through a standard III-V process, and the spectrometer adopts a longitudinal epitaxial structure gradient design, so that the physical transverse size does not affect the function of the spectrometer, and the spectrometer has an ultra-small size and a wide spectral range. According to the process preparation method, an effective, feasible and low-cost scheme is provided for industrialization of micro spectrograph electronic devices, and development of optoelectronic devices is promoted.

Description

Technical Field

[0001] The present invention belongs to the field of optoelectronics, and particularly relates to a prototype device of a single-detector spectrometer, a preparation method thereof, a detector, and an application. Background Art

[0002] A spectrometer is a key tool for analyzing and measuring the spectral characteristics of substances. Its working principle is based on the analysis of the absorption, reflection, emission, and scattering characteristics of light by different substances to obtain information such as the composition, structure, and concentration of substances. Spectrometers are widely used in scientific research and industrial fields, such as chemical analysis, materials science, environmental monitoring, and astronomy. Traditional spectrometers usually rely on mechanically movable components (such as gratings or Michelson interferometers) to achieve light splitting. Although these instruments can provide ultra-high spectral resolution and a wide spectral range, their bulky size and weight limit their applications in laboratory optical systems, automotive electronics, industrial inspection equipment, and portable devices.

[0003] In recent years, with the rapid development of semiconductor processes, the optoelectronic detector technology based on III-V semiconductor materials has gradually matured. However, conventional optoelectronic detectors can usually only detect the intensity of incident light and cannot directly obtain spectral information. To achieve the acquisition of spectral information and promote the miniaturization of spectrometers, a scheme of combining a micro-grating or a narrowband filter with an optoelectronic detector is often adopted. However, this type of scheme requires beam splitting of light, there is a trade-off between the sensitivity and resolution of the spectrometer, and at the same time, the system complexity and cost are increased.

[0004] To solve the above problems, the computationally reconstructed spectrometer based on a single detector has gradually attracted attention. This type of spectrometer reconstructs the spectrum through the photoelectric response of a single detector, effectively avoiding the problem of signal attenuation caused by the separation of the optical path. For example, they can utilize the mapping relationship matrix between the spectral response and voltage regulation to reconstruct the incident spectrum by solving a system of linear equations, avoiding signal loss caused by the separation of the optical path.

[0005] However, due to the precision and complexity of the manufacturing of detectors in the short-wave infrared band, how to design and prepare a single detector with voltage-modulated spectral characteristics, realize the function of a computationally reconstructed spectrometer, improve the spectral resolution, and expand the spectral detection band has become a difficult problem to be solved urgently at present. Summary of the Invention

[0006] Therefore, the object of the present invention is to overcome the defects in the prior art and provide a prototype device of a single-detector spectrometer, a preparation method thereof, a detector and an application. The present invention is based on a bandgap-graded PN junction of InGaAs / InAlAs material, which has the characteristic of adjustable bias bandgap, realizes responses at different wavelengths under different biases, and can realize the analysis of spectral signals from 1500 nm to 2100 nm in cooperation with a spectral reconstruction algorithm. A single-detector micro-spectrometer is fabricated by standard III-V processes. The spectrometer adopts a longitudinal epitaxial structure gradient design, such that the physical lateral size does not affect its function, and it has an ultra-small size and a wide spectral range. The process preparation method of the present invention provides an effective, feasible and low-cost solution for the industrialization of micro-spectrometer electronic devices, which is beneficial to the advancement of optoelectronic devices. The prototype device of the single-detector micro-spectrometer based on the bias-adjustable bandgap PN junction of the present invention has the advantages of miniaturization and high performance, and is expected to be widely applied in the fields of portable spectral detection, hyperspectral imaging and wearable spectroscopy, etc.

[0007] Before elaborating on the content of the present invention, the following terms used herein are defined:

[0008] The term "PN junction" refers to: by processes such as epitaxy, dopant diffusion or ion implantation, a P-type semiconductor and an N-type semiconductor are fabricated on the same semiconductor substrate, and the boundary or interface between these two semiconductor materials is called a PN junction.

[0009] The term "III-V group elements" refers to: the elements in Group III and Group V of the periodic table.

[0010] The term "compositionally graded layer" refers to: the composition ratio of one or more III-V group elements in the material forming this layer gradually changes from bottom to top in space.

[0011] The term "n-type" refers to: a semiconductor mainly conducting by electrons is an n-type semiconductor.

[0012] The term "p-type" refers to: a semiconductor mainly conducting by holes becomes a p-type semiconductor.

[0013] The term "InP" refers to: indium phosphide, whose English name is Indium Phosphide.

[0014] The term "semi-insulating substrate" refers to: a semiconductor substrate material with medium resistivity obtained by doping a semiconductor material, and its resistivity is generally in the range of 10 6 Ω·cm to 10 12 Ω·cm.

[0015] The term "MBE" refers to: molecular beam epitaxy, whose English name is Molecular Beam Epitaxy.

[0016] The term "MOCVD" refers to: Metal-Organic Chemical Vapor Deposition, and its English name is Metal-Organic Chemical Vapor Deposition.

[0017] The term "PECVD" refers to: Plasma Enhanced Chemical Vapor Deposition, and its English name is Plasma Enhanced Chemical Vapor Deposition.

[0018] The term "ICP-PECVD" refers to: Inductively Coupled Plasma-Plasma Enhanced Chemical Vapor Deposition, and its English name is Inductively Coupled Plasma-Plasma Enhanced Chemical Vapor Deposition.

[0019] The term "RIE" refers to: reactive ion etching, and its English name is reactive ion etching.

[0020] The term "ICP-RIE" refers to: Inductively Coupled Plasma Reactive Ion Etching, and its English name is Inductively Coupled Plasma Reactive Ion Etching.

[0021] The term "ALD" refers to: Atomic Layer Deposition, and its English name is Atomic Layer Deposition.

[0022] To achieve the above object, the first aspect of the present invention provides a prototype device of a single-detector spectrometer, and the prototype device includes, sequentially arranged from bottom to top:

[0023] A substrate;

[0024] A p-type metal electrode for forming an ohmic contact;

[0025] A p-type buffer layer;

[0026] A p-type electron barrier layer for reducing the dark current density of the prototype device and improving the specific detectivity;

[0027] An n-type composition graded layer for achieving wavelength-selective detection;

[0028] An n-type contact layer;

[0029] An n-type metal electrode for forming an ohmic contact; and

[0030] A passivation layer for reducing the dangling bonds and surface defects on the surface of the prototype device;

[0031] Wherein, the p-type buffer layer is used to reduce the lattice mismatch and defect density between the substrate and the material of the n-type composition grading layer, and the n-type contact layer is used to form an ohmic contact with the n-type metal electrode.

[0032] For the prototype device according to the first aspect of the present invention, wherein,

[0033] The materials of the n-type metal electrode and the p-type metal electrode are each selected from one or more of the following: Ti / Au, Ti / Pt / Au, Ni / Ge / Au, Ni / Pt / Au, preferably selected from one or more of the following: Ti / Au, Ti / Pt / Au, Ni / Ge / Au, and more preferably Ti / Au or Ti / Pt / Au;

[0034] The material of the p-type buffer layer is selected from one or more of the following: InGaAs, GaAs, InAs, GaAsSb, InAlAs, preferably selected from one or more of the following: InGaAs, GaAsSb, InAlAs, and most preferably InGaAs;

[0035] The material of the p-type electron barrier layer is selected from one or more of the following: InGaAsP, InAlAs, AlAs, InAlGaAs, AlAsSb, preferably InGaAsP or InAlAs, and most preferably InAlAs;

[0036] The composition of the n-type composition grading layer is a group III-V element, and the proportion of the composition gradually changes from bottom to top in space, preferably selected from one or more of the following: InGaAs, GaAsSb, InGaAsP, InAlAsP, preferably InGaAs or GaAsSb, and most preferably InGaAs;

[0037] The material of the n-type contact layer is selected from one or more of the following: InGaAs, GaAs, InAs, GaAsSb, InAlAs, preferably selected from one or more of the following: InGaAs, GaAsSb, InAlAs, and most preferably InGaAs;

[0038] The material of the passivation layer is selected from one or more of the following: Al 2 O 3 、Si x N y 、SiO 2 ,preferably Al 2 O 3 or Si x N y ; wherein 2 < x < 4, preferably 3 ≤ x < 4, and most preferably x is 3; 3 < y < 5, preferably 4 ≤ y < 5, and most preferably y is 4; and / or

[0039] The substrate is selected from one or more of the following: InP substrate, semi-insulating substrate, metal thin film substrate, plastic substrate, glass substrate, preferably selected from one or more of the following: InP substrate, semi-insulating substrate, glass substrate, more preferably an InP substrate or a semi-insulating substrate;

[0040] Preferably, the semi-insulating substrate is selected from one or more of the following: semi-insulating Si substrate, semi-insulating SiC substrate, semi-insulating GaAs substrate;

[0041] Preferably, the metal material of the metal thin film substrate is selected from one or more of the following: copper, aluminum, iron, molybdenum copper, tungsten copper, chromium copper, and the film thickness of the metal thin film substrate is 1-200 um, more preferably 1-100 um; and / or

[0042] Preferably, the thickness of the glass substrate is 1-1000 um, more preferably 100-500 um, and further preferably 200-500 um.

[0043] For the prototype device according to the first aspect of the present invention, wherein the p-type buffer layer, the p-type electron barrier layer, the n-type composition grading layer, and the n-type contact layer form a mesa structure; the mesa structure is preferably a square mesa structure.

[0044] For the prototype device according to the first aspect of the present invention, wherein,

[0045] The shapes of the p-type metal electrode and the n-type metal electrode are selected from one or more of the following: a square frame with a square hole, a circular frame with a square hole, a square frame with a circular hole, a circular frame with a circular hole, a rectangular strip, preferably selected from one or more of the following: a square frame with a square hole, a circular frame with a square hole, a square frame with a circular hole, a circular frame with a circular hole, and most preferably a square frame with a square hole;

[0046] The n-type metal electrode is located above the mesa structure, is in contact with the n-type contact layer, and does not completely cover the n-type contact layer; and / or

[0047] The p-type metal electrode is in contact with the substrate, is nested below the mesa structure, and is not in contact with the mesa structure.

[0048] The second aspect of the present invention provides a method for preparing the prototype device described in the first aspect, and the method includes the following steps:

[0049] 1) Growing a p-type buffer layer, a p-type electron barrier layer, an n-type composition grading layer, and an n-type contact layer on the substrate in sequence to obtain an epitaxial wafer with a substrate;

[0050] 2) Isolating the epitaxial wafer prepared in step 1);

[0051] 3) fabricate the n-type metal electrode and the p-type metal electrode; and

[0052] 4) deposit a passivation layer.

[0053] According to the method of the second aspect of the present invention, wherein,

[0054] In the step 1), the growth method is epitaxial growth, and the epitaxial growth is preferably selected from one or more of the following: MBE, MOCVD, ALD, more preferably MBE or MOCVD, and most preferably MBE; and / or

[0055] In the step 4), the deposition method of the passivation layer is selected from one or more of the following: PECVD, ICP-PECVD, ALD, preferably PECVD or ALD, and most preferably PECVD.

[0056] According to the method of the second aspect of the present invention, wherein, in the step 2), the isolation is mesa isolation, and the mesa isolation method is preferably selected from one or more of the following: photolithography, laser direct writing, electron beam exposure, wet etching, RIE, ICP-RIE, more preferably selected from one or more of the following: wet etching, RIE, ICP-RIE, and most preferably wet etching;

[0057] Preferably, the mesa isolation further includes: etching the p-type buffer layer, the p-type electron barrier layer, the n-type composition grading layer, and the n-type contact layer to obtain a mesa structure with a substrate that is not electrically connected to each other.

[0058] According to the method of the second aspect of the present invention, wherein, the step 3) further includes:

[0059] Above the mesa structure with a substrate that is not electrically connected to each other prepared in step 2), prepare a mask for the n-type metal electrode pattern, and deposit a metal to form an ohmic contact with the n-type contact layer;

[0060] Above the substrate, prepare a mask for the n-type metal electrode pattern, nest it below the mesa structure, deposit a metal to form an ohmic contact with the substrate, and not contact the mesa structure.

[0061] According to the method of the second aspect of the present invention, wherein, after the step 4), the method further includes:

[0062] 5) Open holes in the passivation layer covering the n-type metal electrode and the p-type metal electrode, and the prototype device of the single detector spectrometer is obtained;

[0063] Preferably, the method for opening holes is selected from one or more of the following: etching, reactive ion etching, inductively coupled plasma-reactive ion etching, electron beam lithography, more preferably reactive ion etching or inductively coupled plasma-reactive ion etching, and most preferably reactive ion etching.

[0064] The third aspect of the present invention provides a optoelectronic instrument for optoelectronic detection, and the optoelectronic instrument includes the prototype device described in the first aspect;

[0065] Preferably, the optoelectronic instrument is selected from one or more of the following: photodetector, spectral analyzer, environmental monitor, infrared imager, medical diagnostic instrument, two-color sensor, spectrophotometer, in-situ material analyzer.

[0066] According to a preferred embodiment of the present invention, the prototype device of the single-detector micro-spectrometer of the present invention includes, from bottom to top in sequence:

[0067] Substrate;

[0068] p-type metal electrode;

[0069] p-type buffer layer;

[0070] p-type electron barrier layer;

[0071] n-type composition grading layer;

[0072] n-type contact layer;

[0073] n-type metal electrode; and

[0074] Passivation layer.

[0075] Furthermore, the prototype device of the single-detector micro-spectrometer is an indium phosphide substrate or a semi-insulating substrate, and:

[0076] The material of the p-type buffer layer is selected from one or more of the following: InGaAs, GaAs, InAs, GaAsSb, InAlAs, preferably selected from one or more of the following: InGaAs, GaAsSb, InAlAs, and most preferably InGaAs;

[0077] The material of the p-type electron barrier layer is selected from one or more of the following: InGaAsP, InAlAs, AlAs, InAlGaAs, preferably selected from one or more of the following: InGaAsP, InAlAs, and more preferably InAlAs;

[0078] The material of the n-type composition grading layer is selected from one or more of the following: InGaAs, GaAsSb, InGaAsP, InAlAsP, preferably InGaAs or GaAsSb, and most preferably InGaAs;

[0079] The material of the n-type contact layer is selected from one or more of the following: InGaAs, GaAs, InAs, GaAsSb, InAlAs, and is selected from one or more of the following: InGaAs, GaAsSb, InAlAs, and is most preferably InGaAs;

[0080] The materials of the n-type metal electrode and the p-type metal electrode are selected from one or more of the following: Ti / Au, Ti / Pt / Au, Ni / Ge / Au, preferably selected from one or more of the following: Ti / Au, Ti / Pt / Au, Ni / Ge / Au, and more preferably Ti / Au or Ti / Pt / Au;

[0081] The material of the passivation layer is selected from one or more of the following: Al 2 O 3 、Si x N y 、SiO 2 ,preferably Al 2 O 3 or Si x N y ; wherein, 2 < x < 4, preferably 3 ≤ x < 4, and most preferably x is 3; 3 < y < 5, preferably 4 ≤ y < 5, and most preferably y is 4.

[0082] Furthermore, the single-detector micro-spectrometer prototype device has a square mesa structure, and the mesa sequentially includes a p-type buffer layer, a p-type electron barrier layer, an n-type compositionally graded layer, and an n-type contact layer from bottom to top. The n-type metal electrode is located on the mesa, and the p-type metal electrode is located below the mesa.

[0083] Preferably, the mesa is formed by etching or lithography.

[0084] The shapes of the n-type metal electrode and the p-type metal electrode are selected from one or more of the following: square holes, circular rings, and are preferably square holes;

[0085] The compositionally graded layer means that the composition ratio of one or more III-V group elements in the material forming the layer gradually changes with space from bottom to top.

[0086] The method for preparing the single-detector micro-spectrometer prototype device of the present invention includes the following steps:

[0087] (1) Growing and preparing an epitaxial wafer including the p-type buffer layer, the p-type electron barrier layer, the n-type compositionally graded layer, and the n-type contact layer;

[0088] (2) Performing mesa isolation on the epitaxial wafer obtained in step (1);

[0089] (3) Fabricate the n-type metal electrode and the p-type metal electrode;

[0090] (4) Deposit the passivation layer;

[0091] (5) Open electrode windows, namely obtaining the prototype device of the single-detector micro-spectrometer.

[0092] Furthermore, in the step (1), it includes: sequentially growing a p-type buffer layer, a p-type electron barrier layer, an n-type composition grading layer, and an n-type contact layer on an InP or semi-insulating substrate;

[0093] In the step (2), it includes: performing mesa isolation by etching or dry etching to separate the epitaxial layer on the substrate into non-conducting mesas;

[0094] In the step (3), it includes: preparing a mask for the patterns of the n-type metal electrode and the p-type metal electrode, and depositing metal to form an ohmic contact;

[0095] In the step (4): the deposition thickness of the passivation layer is 50 nm to 400 nm, preferably 150 nm to 300 nm, and most preferably 200 to 250 nm;

[0096] In the step (5): the electrode opening is performed by an etching method.

[0097] Preferably, in the step (1): the epitaxial growth method includes but is not limited to: MBE, MOCVD;

[0098] Preferably, in the step (2): the mesa isolation method is selected from one or more of the following: photolithography, laser direct writing, electron beam lithography, wet etching, RIE, ICP-RIE, more preferably selected from one or more of the following: wet etching, RIE, ICP-RIE, and most preferably wet etching;

[0099] Preferably, in the step (3): the method for growing metal is selected from one or more of the following: photolithography, electron beam evaporation, lift-off, physical vapor deposition, chemical vapor deposition, laser direct writing, electron beam lithography, sputtering, ALD, preferably selected from one or more of the following: photolithography, electron beam evaporation, lift-off, and more preferably selected from one or more of the following: photolithography, electron beam evaporation, lift-off;

[0100] Preferably, in the step (4): the deposition method of the passivation layer is selected from one or more of the following: PECVD, ICP-PECVD, ALD, preferably PECVD or ALD, and most preferably PECVD.

[0101] Application of the prototype device of the single-detector micro-spectrometer of the present invention in the field of optoelectronic detection;

[0102] Preferably, the optoelectronic detection field is selected from one or more of the following: spectral analysis, environmental monitoring, infrared imaging, medical diagnosis, dual-color sensing, spectrophotometry, in-situ material analysis.

[0103] According to another preferred embodiment of the present invention, the single-detector micro-spectrometer prototype device of the present invention is based on an indium phosphide substrate, and the indium phosphide-based single-detector micro-spectrometer prototype device includes, sequentially arranged from bottom to top:

[0104] P-type InP substrate;

[0105] p-type metal electrode;

[0106] p-type InGaAs buffer layer;

[0107] p-type electron barrier layer;

[0108] n-type InGaAs composition grading layer;

[0109] n-type contact layer;

[0110] n-type metal electrode; and

[0111] Passivation layer.

[0112] Among them, the single-detector micro-spectrometer prototype device is an independent device and / or integrated in a circuit;

[0113] Furthermore, the p-type metal electrode and the n-type metal electrode are selected from one or more of the following: Ti / Au, Ti / Pt / Au, Ni / Ge / Au, preferably Ti / Au or Ti / Pt / Au.

[0114] The thickness of the p-type metal electrode and the n-type metal electrode is preferably 50 - 400 μm, and more preferably 300 nm.

[0115] Preferably, the n-type InGaAs composition grading layer is preferably 600 nm thick, where the composition grading means that the In composition in the InGaAs compound material gradually changes with the thickness from bottom to top. Preferably, the In composition gradually changes from 0.53 to 0.75 from bottom to top, and the In composition is controlled by the beam current ratio of In and Ga during the epitaxial growth of the material. The n-type doping concentration is 1 - 5×10 16 cm -3 . By adjusting the reverse bias voltage, the depletion region width of the n-type composition grading InGaAs layer with a lower doping concentration changes, so that longer and shorter wavelength lights are absorbed in the high-In composition region, while shorter wavelength lights are absorbed in the low-Al composition region, thereby achieving wavelength-selective detection through voltage control.

[0116] The p-type electron barrier layer is in contact with the composition grading layer in terms of the barrier layer material and composition. It forms an electron barrier in the energy band structure to block the drift of the majority carriers, i.e., electrons, in the conduction band. Only when electron-hole pairs are generated by light incident in the depletion region of the composition grading layer can they be transported under the drive of the built-in electric field in the depletion region to form a photocurrent. The p-type electron barrier layer can effectively reduce the dark current density of the detector and improve the specific detectivity of the detector. When the composition grading layer is preferably InGaAs, the material of the p-type electron barrier layer is selected from one or more of the following: InAlAs, InGaAsP, and most preferably InAlAs;

[0117] The material of the p-type buffer layer is lattice-matched with the InP substrate and the p-type barrier layer. Its function is to reduce the lattice mismatch and defect density in the epitaxial growth of the material and improve the stability of the epitaxial layer. When the composition grading layer is preferably InGaAs, the material of the p-type buffer layer is preferably InGaAs to achieve lattice matching with the InP substrate and the InAlAs p-type barrier layer. The thickness of the p-type buffer layer is preferably 150 - 600 nm, and more preferably 500 nm.

[0118] The preparation method of the single-detector micro-spectrometer prototype device of the present invention includes the following steps:

[0119] (1) Epitaxially grow a p-type buffer layer, a p-type electron barrier layer, an n-type composition grading layer, and an n-type contact layer on the InP substrate in sequence to obtain an indium phosphide-based epitaxial wafer.

[0120] (2) Perform mesa isolation on the epitaxial wafer obtained in step (1) by etching or dry etching. Separate the epitaxial layer on the InP substrate into non-conducting mesas.

[0121] (3) Prepare the source and drain metal electrodes of the device. Prepare masks for the patterns of the n-type metal electrode and the p-type metal electrode by photolithography. Then grow metals such as Ti / Au, Ti / Pt / Au, or Ni / Ge / Au through electron beam evaporation, lift-off and other processes to form ohmic contacts. Prepare a metal n-electrode above the mesa and a p-electrode below the mesa; the shapes of the n-electrode and the p-electrode are square. The contact resistance is optimized by adjusting the annealing temperature and annealing duration. The contact resistance is usually measured by the transmission line method. The size and spacing of the electrodes are controlled by the pattern size of the photolithography mask plate, and the thickness of the metal electrode is controlled by electron beam evaporation.

[0122] (4) Deposit a passivation layer to reduce the dangling bonds and surface defects on the device surface, improve the dark current characteristics, and enhance the stability of the device.

[0123] (5) Use etching for electrode opening, and etch the Si x N yThe passivation layer is etched to form openings, facilitating subsequent bonding or probe testing.

[0124] Further, in the step (1), the epitaxial growth method includes but is not limited to: MBE, MOCVD;

[0125] In the step (2), the mesa isolation method is selected from one or more of the following: photolithography, laser direct writing, electron beam lithography, wet etching, RIE, ICP - RIE. Preferably, the wet etching method is adopted. Further preferably, the type and ratio of the solution can be H 2 O 2 :H 3 PO 4 :H 2 O (1:1:25) solution to etch the InGaAs epitaxial layer and the InAlAs epitaxial layer, and HCl:H 2 O (1.5:1) solution to etch the InP epitaxial layer.

[0126] In the step (3): The source electrode and drain electrode patterns are selected from one or more of the following: square frame, rectangular frame, circular frame; preferably a square frame. The size of the square frame is preferably 1m×1mm, 1.5mm×1.50mm, 2mm×2mm, and the width of the frame is preferably 150um;

[0127] In the step (3): The gate electrode metal is selected from one or more of the following: Ti / Au, Ti / Pt / Au, Ni / Ge / Au, preferably Ti / Au or Ti / Pt / Au.

[0128] In the step (4): The passivation layer is selected from one or more of the following: Al 2 O 3 、Si x N y , where x and y are the ratios of Si ions and N ions. The preparation method of the passivation layer is selected from one or more of the following: PECVD, ICP - PECVD, ALD. Preferably, Si 3 N 4 (270°C) can be deposited by PECVD or Al 2 O 3 (250°C) passivation layer can be deposited by ALD.

[0129] The deposition gas is selected from one or more of the following: SiH 4 、NH 3 ; The deposition thickness of the passivation layer is preferably 150nm - 300nm, and most preferably 250nm;

[0130] The portable, wide-spectrum-detecting single-detector micro-spectrometer prototype device of the present invention includes, from bottom to top in sequence: a p-type metal electrode, a p-type buffer layer, a p-type electron barrier layer, an n-type composition gradient layer, an n-type contact layer, an n-type metal electrode, and a passivation layer. The preparation method is to grow an epitaxial wafer, perform mesa isolation, prepare p-type and n-type metal electrodes, deposit a passivation layer, and open electrode windows. The prototype device of the present invention has good stability. In an example of the preferred preparation method of the present invention, before preparing the corrosion sacrificial layer, a dense antioxidant Si x N y film is deposited by PECVD / ICP-PECVD technology, avoiding oxidation on the sidewalls and surface of the device and improving the stability of the device. The prototype device of the present invention has high compatibility: the preparation method of the present invention is applicable to a variety of substrates and can achieve integration with more microelectronic devices or integrated circuits of various types.

[0131] Compared with the prior art, the prototype device of the single-detector spectrometer of the present invention, its preparation method, detector, and application can have but are not limited to the following beneficial effects:

[0132] 1. High-resolution wavelength spectral analysis can be achieved with a single-detector device, thus eliminating the need for multiple discrete detectors or gratings.

[0133] 2. High responsivity. The III-V semiconductor material-based device of the present invention has excellent detection ability in the short-wave infrared range, with good optical response and weak-light detection ability in the short-wave infrared band.

[0134] 3. Based on the single-detector micro-spectrometer device and preparation method of the present invention, through experimental testing and combined with a spectral reconstruction algorithm, spectral detection in the 1.5 - 2.0 um band can be achieved and is expected to be applied to spectral resolution in the short-wave infrared band.

[0135] 4. The preparation method is simple and has high repeatability. The present invention can be prepared based on conventional semiconductor microfabrication technology, with low cost. It has the advantages of miniaturization and high performance, with ultra-small size and a wide spectral range, and is expected to be widely used in fields such as portable spectral detection, hyperspectral imaging, and wearable spectroscopy.

[0136] 5. This device architecture can achieve back-illumination by flipping the entire external stack through flip-chip bonding technology, and thus be applied to a focal plane array (FPA). Compatibility with the FPA indicates that this p-i-n junction spectrometer can be integrated into a large FPA to achieve multi-spectral imaging applications.

[0137] 6. Good stability. In the preparation method of the present invention, before preparing the corrosion sacrificial layer, a dense antioxidant Si x N yThe thin film avoids oxidation on the sidewalls and surface of the device, improving the stability of the device.

[0138] 7. The prototype device of the present invention has high compatibility: The preparation method of the present invention is applicable to a variety of substrates and can achieve integration with more microelectronic devices or integrated circuits. BRIEF DESCRIPTION OF THE DRAWINGS

[0139] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings, where:

[0140] Figure 1 FIG. shows a flowchart of a method for fabricating a prototype device of a single-detector spectrometer in Embodiment 1 of the present invention.

[0141] Figure 2 FIG. shows a cross-sectional schematic view of an InP substrate in Embodiment 1 of the present invention.

[0142] Figure 3 FIG. shows a cross-sectional schematic view of an epitaxial growth structure on a wafer in Embodiment 1 of the present invention.

[0143] Figure 4 FIG. shows a cross-sectional schematic view after mesa isolation in Embodiment 1 of the present invention.

[0144] Figure 5 FIG. shows a cross-sectional schematic view of fabricating a p-type metal electrode and an n-type metal electrode in Embodiment 1 of the present invention.

[0145] Figure 6 FIG. shows a top view schematic of fabricating an n-type metal electrode (Ti / Au upper electrode layer unit) in Embodiment 1 of the present invention.

[0146] Figure 7 FIG. shows Si in Embodiment 1 of the present invention x N y FIG. shows a cross-sectional schematic view of SiN passivation layer deposition.

[0147] Figure 8 FIG. shows a cross-sectional schematic view of the prototype device of the single-detector spectrometer fabricated in Embodiment 1 of the present invention.

[0148] DESCRIPTION OF REFERENCE NUMERALS:

[0149] 1. P-type substrate; 2. p-type buffer layer; 3. p-type electron barrier layer; 4. p-type composition gradient layer; 5. n-type contact layer; 6. p-type metal electrode; 7. n-type metal electrode; 8. Passivation layer. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0150] Hereinafter, the present invention will be further described with reference to the drawings through specific embodiments. However, it should be understood that these embodiments are only for more detailed and specific illustration purposes and should not be construed as limiting the present invention in any form.

[0151] This section gives a general description of the materials and test methods used in the tests of the present invention. Although many materials and operation methods used to achieve the purpose of the present invention are well known in the art, the present invention still describes them in as much detail as possible here. Those skilled in the art are aware that, in the context, if not otherwise specified, the materials and operation methods used in the present invention are well known in the art.

[0152] Example 1

[0153] This embodiment is an exemplary illustration of the prototype device and preparation method of the single-detector spectrometer of the present invention.

[0154] This embodiment takes the prototype device of a single-detector micro-spectrometer with an indium phosphide-based, square mesa structure as an example, and its cross-sectional schematic diagram is as Figure 8 shown. The indium phosphide-based single-detector micro-spectrometer prototype device of the present invention includes: a P-type substrate 1, a p-type buffer layer 2, a p-type electron barrier layer 3, a p-type composition grading layer 4, an n-type contact layer 5, a p-type metal electrode 6, an n-type metal electrode 7, and a passivation layer 8. The p-type electron barrier layer, the n-type composition grading layer, and the n-type contact layer form a mesa structure.

[0155] In this embodiment, the substrate is an InP substrate as an example, the p-type buffer layer is InGaAs as an example, the p-type electron barrier layer is InAlAs as an example, the n-type composition grading layer is InGaAs as an example, the n-type contact layer is InGaAs as an example, and the passivation layer is Si 3 N 4 as an example. Both the n-type metal electrode and the p-type metal electrode are Ti / Au as an example, and the shapes are both square frames with square holes as an example. The n-type metal electrode is located above the mesa structure, connected to the n-type contact layer, and does not completely cover the n-type contact layer; the p-type metal electrode is connected to the substrate, sleeved under the mesa structure, and does not contact the mesa structure.

[0156] The preparation method process of the prototype device of the single-detector micro-spectrometer in this embodiment is as Figure 1 shown, and specifically includes the following steps:

[0157] Step 001: Grow the epitaxial layer of the prototype device of the single-detector micro-spectrometer on a p-type InP substrate;

[0158] Step 002: Perform mesa etching isolation on the obtained epitaxial wafer;

[0159] Step 003: Prepare the p-type metal and n-type metal electrodes of the indium phosphide-based single-detector micro-spectrometer prototype device;

[0160] Step 004: Deposit and prepare Six N y Passivation layer;

[0161] Step 005: Etch openings in the Si covering the p-type metal electrode and the n-type electrode x N y passivation layer;

[0162] Specifically:

[0163] (1) The structures required for the epitaxial growth described in Step 001 include: a 500-nm p-type InGaAs buffer layer 2, a 30-nm p-type InAlAs electron barrier layer 3, a 600-nm InGaAs n-type compositionally graded layer 4, and a 100-nm InGaAs n-type contact layer 5, as Figure 3 shown.

[0164] In this Example 1, the required structures are prepared by MBE epitaxial growth, where the InP wafer size is 2 inches. First, a 500-nm p-type InGaAs buffer layer is grown on the p-type InP wafer substrate, with a doping concentration of 1×10 18 cm -3 ; a 30-nm p-type InAlAs electron barrier layer, with a doping concentration of 5×10 17 cm -3 ; a 600-nm InGaAs n-type compositionally graded layer, with a doping concentration of 1×10 16 cm -3 ; a 100-nm InGaAs n-type contact layer, with a doping concentration of 1×10 18 cm -3 ;

[0165] Taking the thickness of the n-type InGaAs compositionally graded layer as 600 nm as an example, the compositional grading means that the In composition in the InGaAs compound material gradually changes from bottom to top with the thickness. The In composition gradually changes from 0.53 to 0.75 from bottom to top, where the In composition is controlled by the beam flux ratio of In and Ga during the epitaxial growth of the material. The n-type doping concentration is 1 - 5×10 16 cm -3 . By adjusting the reverse bias voltage, the depletion region width of the n-type compositionally graded InGaAs layer with a lower doping concentration changes, so that longer and shorter wavelength lights are absorbed in the high-In composition region, while shorter wavelength lights are absorbed in the low-Al composition region, thereby realizing wavelength-selective detection through voltage control.

[0166] The p-type electron barrier layer is in contact with the composition-graded layer in terms of the barrier layer material. An electron barrier is formed in the energy band structure to block the drift of the majority carriers, i.e., electrons, in the conduction band. Only when electron-hole pairs are generated by light incident in the depletion region of the composition-graded layer can they be transported under the drive of the built-in electric field in the depletion region to form a photocurrent. The p-type electron barrier layer can effectively reduce the dark current density of the detector and improve the specific detectivity of the detector. When the composition-graded layer is preferably InGaAs, the material of the p-type electron barrier layer is InAlAs;

[0167] The material of the p-type buffer layer is lattice-matched with the InP substrate and the p-type barrier layer. Its function is to reduce the lattice mismatch and defect density during the epitaxial growth of the material and improve the stability of the epitaxial layer. When the composition-graded layer is preferably InGaAs, the material of the p-type buffer layer is InGaAs to achieve lattice matching with the InP substrate and the InAlAs p-type barrier layer. The thickness of the p-type buffer layer is taken as 500 nm as an example.

[0168] (2) In step 002, the mesa isolation includes using a wet etching method to separate the epitaxial layer on the InP substrate into non-conducting mesas. A mask for preparing the etched mesa pattern is fabricated by ultraviolet exposure technology. Using H 2 O 2 :H 3 PO 4 :H 2 O (1:1:25) solution to etch the InGaAs epitaxial layer and the InAlAs epitaxial layer, and the obtained mesa structure schematic diagram is as Figure 4 shown.

[0169] (3) For the p-type metal and n-type metal electrodes of the indium phosphide substrate single-detector micro-spectrometer prototype device described in step 003, in this embodiment, a mask for preparing the electrode pattern is fabricated by ultraviolet exposure technology. The electrode shape is a square frame with a square hole. The p-type metal electrode is a square frame with a side length of 1000 μm and a width of 200 μm with a square hole. The n-type metal electrode is a square frame with a side length of 400 μm and a width of 150 μm with a square hole. And using electron beam evaporation technology, a Ti / Au upper electrode is evaporated and prepared, and its electrode structure is Ti / Au (20 nm / 200 nm), as Figure 5 shown. Figure 6 It is a top view schematic diagram of the Ti / Au upper electrode layer unit.

[0170] (4) For the Si x N y The passivation layer is prepared by PECVD method by depositing a 220-nm-thick Si 3 N 4 passivation layer at 270 °C. Figure 7 It is the deposition of Si by PECVD method3 N 4 Schematic diagram after the passivation layer.

[0171] (5) For the electrode window opening described in step 005, the Si above the n-type metal electrode and the p-type metal electrode is etched and removed by RIE 3 N 4 the passivation layer to expose part of the metal electrode, thus obtaining the prototype device of the single-detector micro-spectrometer.

[0172] Examples 2 to 5

[0173] This embodiment is other exemplary descriptions of the prototype device and preparation method of the single-detector spectrometer of the present invention.

[0174] The preparation methods of Examples 2 to 5 are the same as those of Example 1, except for Table 1.

[0175] Table 1 Prototype devices of single-detector spectrometers prepared in Examples 2 to 5

[0176]

[0177]

[0178] Test Example 1

[0179] This test example is used to illustrate the effect of the prototype device of the single-detector spectrometer of the present invention.

[0180] In this test example, the optoelectronic properties of the prototype devices of single-detector spectrometers prepared in Examples 1 to 5 are tested, and the test steps are as follows:

[0181] (1) The spectral response band of the detector is tested with a Fourier transform infrared spectrometer, and the wavelength at 50% of the peak spectral response is taken in the measured spectral response curve to determine the starting wavelength and the cut-off wavelength.

[0182] (2) The responsivity of the detector is tested by the blackbody response with reference to "GB / T 13584—2011 Test Methods for Parameters of Infrared Detectors" to obtain the responsivity at the peak response wavelength of the detector.

[0183] (3) The dark current of the detector is tested by a semiconductor parameter analyzer for the voltage-current curve under no-light conditions.

[0184] (4) The specific detectivity D* is the spectral detectivity of the detector per unit area (1 cm 2 ) and per unit bandwidth (1 Hz), with the unit of cmHz 1 / 2 / W, and the definition formula is:

[0185]

[0186] Among them, A is the photosensitive area of the device, Δf is the working bandwidth of the detector, and NEP is the equivalent noise power of the dark current.

[0187] The formula for the equivalent noise power NEP of the dark current is:

[0188]

[0189] Among them, J is the dark current density, R is the responsivity of the detector, and q is the elementary charge amount (take 1.6×10 -19 C), substituting into the formula (2) of the equivalent noise power NEP of the dark current, after simplification, the formula for the specific detectivity D* can be obtained as:

[0190]

[0191] Table 2 Photoelectric performance effects of the prototype devices of the single-detector spectrometers prepared in Examples 1 to 5

[0192]

[0193] According to the parameters shown in Table 2, substituting into the above formula, the specific detectivity D* of the prototype devices of the single-detector spectrometers prepared in Examples 1 to 5 is obtained, indicating that the prototype devices of the single-detector spectrometers prepared in Examples 1 to 5 have excellent photoelectric performance effects. The prototype device of the single-detector spectrometer of the present invention has high spectral detection sensitivity, its responsivity is above 0.9 A / W, and the dark current is not higher than 5.33×10 -6 A / cm 2 , and the specific detectivity is above 1.80×10 11 cmHz 1 / 2 / W. It has the characteristics of high response and low dark current, can realize high-resolution wavelength spectral analysis with a single-detector device, thus eliminating the need for multiple discrete detectors or gratings, and can realize spectral detection in the 1.5 - 2.0 um band, etc.

[0194] Computational reconstruction spectrometers based on single-detector designs. Embodiments of the present invention relate to semiconductor compounds of several different group III and group V elements, where the doping concentration of each component in the compositionally graded layer varies linearly with space, resulting in a variation in the bandgap of the energy band with space. When the reverse bias is increased, the depletion region width increases with the bias. When a light source is incident on the detector, the photo-generated carriers generated by inter-band transitions have different absorption peak wavelengths at different bandgaps. The spectral detection range is determined by the doping concentration of each element in the compositionally graded layer and the magnitude of the applied bias. The responsivity and dark current of the detector determine the level of spectral detection sensitivity of the single detector, and the dark current is determined by the doping concentration, defect density, and passivation process conditions of the epitaxial layer itself. The specific detectivity is the spectral detectivity per unit area and per unit bandwidth of the detector. The larger the specific detectivity, the higher the detection sensitivity of the detector to weak light.

[0195] Although the effects of some embodiments are shown above, those skilled in the art should understand that according to the concept of the present invention, the foregoing other embodiments for which the effects are not specifically shown or other technical solutions of the present invention not shown in the embodiments can also achieve the following technical effects stated in the summary of the invention that are equivalent to those of the embodiments:

[0196] 1. High-resolution wavelength spectral analysis can be achieved using a single-detector device, thus eliminating the need for multiple discrete detectors or gratings.

[0197] 2. High responsivity. The III-V semiconductor material-based present invention has excellent detection capabilities in the short-wave infrared, with good optical response and weak light detection capabilities in the short-wave infrared band.

[0198] 3. Based on the single-detector micro-spectrometer device and preparation method of the present invention, through experimental testing and combined with spectral reconstruction algorithms, spectral detection in the 1.5 - 2.0 μm band can be achieved and is expected to be applied to spectral resolution in the short-wave infrared band.

[0199] 4. The preparation method is simple and highly repeatable. The present invention can be prepared based on conventional semiconductor microfabrication techniques, with low costs. It has the advantages of miniaturization and high performance, with ultra-small size and a wide spectral range, and is expected to be widely used in fields such as portable spectral detection, hyperspectral imaging, and wearable spectroscopy.

[0200] 5. This device architecture can achieve back-illumination by means of flip-chip bonding technology, by reversing the entire external stack, and thus can be applied to a focal plane array (FPA). Compatibility with the FPA indicates that this p-on-n junction spectrometer can be integrated into a large FPA to achieve multi-spectral imaging applications.

[0201] 6. Good stability. Before preparing the corrosion sacrificial layer in the preparation method of the present invention, a dense and antioxidant Si x N y film is deposited by PECVD / ICP-PECVD technology, avoiding oxidation on the sidewalls and surface of the device and improving the stability of the device.

[0202] 7. High compatibility of the prototype device of the present invention: The preparation method of the present invention is applicable to a variety of substrates and can achieve integration with more microelectronic devices or integrated circuits.

[0203] Although the present invention has been described to a certain extent, obviously, appropriate changes can be made to each condition without departing from the spirit and scope of the present invention. It can be understood that the present invention is not limited to the described embodiments, but falls within the scope of the claims, which includes equivalent replacements for each factor described.

Claims

1. A prototype device of a single-detector spectrometer, characterized in that: The prototype device includes: substrate; A p-type metal electrode for forming an ohmic contact; p-type buffer layer; A p-type electron barrier layer for reducing the dark current density of the prototype device and improving the specific detectivity; An n-type composition graded layer for achieving wavelength selective detection; n-type contact layer; An n-type metal electrode for forming an ohmic contact; and a passivation layer for reducing dangling bonds and surface defects on the surface of the prototype device; Wherein: the p-type buffer layer is used to reduce the dislocation mismatch and defect density of the materials of the substrate and the n-type component gradient layer, and the n-type contact layer is used to form an ohmic contact with the n-type metal electrode.

2. The prototype device according to claim 1, characterized in that: The materials of the n-type metal electrode and the p-type metal electrode are selected from one or more of the following: Ti / Au, Ti / Pt / Au, Ni / Ge / Au, Ni / Pt / Au, preferably selected from one or more of the following: Ti / Au, Ti / Pt / Au, Ni / Ge / Au, more preferably Ti / Au or Ti / Pt / Au; The material of the p-type buffer layer is selected from one or more of the following: InGaAs, GaAs, InAs, GaAsSb, InAlAs, preferably selected from one or more of the following: InGaAs, GaAsSb, InAlAs, most preferably InGaAs; The material of the p-type electron barrier layer is selected from one or more of the following: InGaAsP, InAlAs, AlAs, InAlGaAs, AlAsSb, preferably InGaAsP or InAlAs, most preferably InAlAs; The n-type component gradient layer has a III-V group element as its component, and the proportion of the component changes gradually from bottom to top in space, and is preferably selected from one or more of the following: InGaAs, GaAsSb, InGaAsP, InAlAsP, preferably InGaAs or GaAsSb, and most preferably InGaAs; The material of the n-type contact layer is selected from one or more of the following: InGaAs, GaAs, InAs, GaAsSb, InAlAs, preferably selected from one or more of the following: InGaAs, GaAsSb, InAlAs, most preferably InGaAs; The material of the passivation layer is selected from one or more of the following: Al2O3, Si x N y , SiO2, preferably Al2O3 or Si x N y ; wherein 2<x<4, preferably 3≤x<4, most preferably x is 3; said 3<y<5, preferably 4≤y<5, most preferably y is 4; and / or The substrate is selected from one or more of the following: an InP substrate, a semi-insulating substrate, a metal film substrate, a plastic substrate, and a glass substrate, preferably selected from one or more of the following: an InP substrate, a semi-insulating substrate, and a glass substrate, more preferably an InP substrate or a semi-insulating substrate; Preferably, the semi-insulating substrate is selected from one or more of the following: a semi-insulating Si substrate, a semi-insulating SiC substrate, and a semi-insulating GaAs substrate; Preferably, the metal material of the metal film substrate is selected from one or more of the following: copper, aluminum, iron, molybdenum copper, tungsten copper, chromium copper, and the film thickness of the metal film substrate is 1 to 200 um, more preferably 1 to 100 um; and / or Preferably, the thickness of the glass substrate is 1 to 1000 um, more preferably 100 to 500 um, and further preferably 200 to 500 um.

3. The prototype device according to claim 1 or 2, characterized in that: The p-type buffer layer, the p-type electron barrier layer, the n-type component gradient layer and the n-type contact layer form a mesa structure; the mesa structure is preferably a square mesa structure.

4. The prototype device according to claim 3, characterized in that: The shapes of the p-type metal electrode and the n-type metal electrode are selected from one or more of the following: a square frame with a square hole, a circular frame with a square hole, a square frame with a circular hole, a circular frame with a circular hole, and a rectangular strip, preferably selected from one or more of the following: a square frame with a square hole, a circular frame with a square hole, a square frame with a circular hole, and a circular frame with a circular hole, and most preferably a square frame with a square hole; The n-type metal electrode is located above the mesa structure, in contact with the n-type contact layer, and does not completely cover the n-type contact layer; and / or The p-type metal electrode is connected to the substrate, nested under the mesa structure, and not in contact with the mesa structure.

5. A method for preparing a prototype device according to any one of claims 1 to 4, characterized in that: The method comprises the following steps: 1) sequentially growing a p-type buffer layer, a p-type electron barrier layer, an n-type component gradient layer and an n-type contact layer on a substrate to obtain an epitaxial wafer with a substrate; 2) isolating the epitaxial wafer prepared in step 1); 3) preparing an n-type metal electrode and a p-type metal electrode; and 4) Deposition of a passivation layer.

6. The method according to claim 5, characterized in that: In the step 1), the growth method is epitaxial growth, and the epitaxial growth is preferably selected from one or more of the following: MBE, MOCVD, ALD, more preferably MBE or MOCVD, most preferably MBE; and / or In the step 4), the deposition method of the passivation layer is selected from one or more of the following: PECVD, ICP-PECVD, ALD, preferably PECVD or ALD, most preferably PECVD.

7. The method according to claim 5 or 6, characterized in that: In the step 2), the isolation is mesa isolation, and the method of mesa isolation is preferably selected from one or more of the following: photolithography, laser direct writing, electron beam exposure, wet etching, RIE, ICP-RIE, more preferably selected from one or more of the following: wet etching, RIE, ICP-RIE, and most preferably wet etching; Preferably, the mesa isolation further comprises: etching the p-type buffer layer, the p-type electron barrier layer, the n-type component gradient layer and the n-type contact layer to obtain a mesa structure with a substrate that is not connected to each other.

8. The method according to claim 7, characterized in that The step 3) further comprises: On the non-conductive mesa structure with the substrate prepared in step 2), a mask of an n-type metal electrode pattern is prepared, and metal is deposited to form an ohmic contact with the n-type contact layer; A mask of an n-type metal electrode pattern is prepared above the substrate so as to be nested below the mesa structure, and metal is deposited so as to form an ohmic contact with the substrate and not contact the mesa structure.

9. The method according to any one of claims 5 to 8, characterized in that The method further comprises after step 4): 5) Opening holes in the passivation layer covering the n-type metal electrode and the p-type metal electrode to obtain a prototype device of the single-detector spectrometer; Preferably, the method of opening the holes is selected from one or more of the following: etching, reactive ion etching, inductively coupled plasma-reactive ion etching, electron beam exposure, more preferably reactive ion etching or inductively coupled plasma-reactive ion etching, most preferably reactive ion etching.

10. An optoelectronic instrument for photoelectric detection, characterized in that: The optoelectronic apparatus comprises the prototype device according to any one of claims 1 to 4; Preferably, the optoelectronic instrument is selected from one or more of the following: a photodetector, a spectrometer, an environmental monitor, an infrared imager, a medical diagnostic instrument, a two-color sensor, a spectrophotometer, and an in-situ material analyzer.

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