Cascade double-color photoelectric detector for realizing optical signal amplification based on avalanche effect

Abstract

The invention discloses a cascade double-color photoelectric detector for realizing optical signal amplification based on an avalanche effect, and belongs to the technical field of photoelectric detection and photoelectric imaging. According to the invention, a semiconductor double heterojunction structure from top to bottom is designed, the PIN-type infrared photoelectric detector and the solar blind ultraviolet avalanche photoelectric detector are induced to excite each other through bias voltage regulation and control, and rapid detection of ultraviolet light and infrared light incident to the detector is realized. In this way, the problem that the wavelength range of absorbed light of a traditional detector is limited is solved, ultraviolet band light signals and infrared band light signals are detected at the same time in the target environment, and meanwhile the light current gain of infrared band light signal detection is improved. The invention is suitable for the field of photoelectric detection, improves the detection capability of target light, and improves the light responsivity.

Description

Technical Field

[0001] The invention relates to the field of semiconductor optoelectronic devices, in particular to a cascaded two-color photoelectric detector for realizing optical signal amplification based on an avalanche effect, and belongs to the field of photoelectric detection. Background Art

[0002] Photodetectors are detectors that convert light signals into electrical signals. They are often used for detection in ultraviolet, visible light, and infrared bands. In real environments, ultraviolet radiation mainly comes from the sun, with a wavelength of 10-400nm. The ultraviolet light corresponding to the wavelength range of 100-280nm has weak penetration ability and is absorbed by the ozone layer when passing through the atmosphere. Therefore, there is almost no solar radiation from this band in the ground environment, which is called the solar-blind ultraviolet zone. Infrared radiation comes from the blackbody radiation of objects, with a wavelength range of 780nm-1mm. This band is sensed by heat and detected by special detectors or cameras. Infrared light in nature is roughly divided into three bands: near infrared: 780nm-2500nm; mid-infrared: 2500nm-25μm; far infrared: 25μm-500μm. According to Planck's blackbody radiation law, there is a difference in the energy of infrared light radiated by objects of different temperatures. This principle can be used to realize infrared detection technology. Ultraviolet light and infrared light cannot be observed by the human eye, but they provide important information in target detection. Therefore, with the advancement of semiconductor photoelectric detection technology, scientists have conducted in-depth research on ultraviolet light and infrared light detection. Currently, a variety of single-band photoelectric detectors have been prepared that can meet different scenarios and different needs.

[0003] Based on the current mature photoelectric detection technology, photomultiplier tubes, GaN-based photoconductive detectors, etc. have been able to achieve ultraviolet detection in the 0.1-0.38nm band. 2 O 3 UV detectors can detect solar-blind bands; infrared detection has achieved detection in the 0.78-300μm band, such as HgCdTe mid-infrared photodetectors, InGaAs PIN photodiode near-infrared detectors, etc. In recent years, the growth and preparation process of semiconductor materials has been improved, and new photodetectors such as van der Waals heterojunction-based photodetectors, quantum dot detectors and other low-dimensional devices have attracted many researchers. Semiconductor photodetectors for detecting ultraviolet and infrared light have been widely used in civil and military fields, such as landform monitoring, environmental monitoring, missile warning, space positioning and other fields. A large number of application demands have prompted the rapid development of infrared and ultraviolet monochromatic photodetection technologies in their respective fields.

[0004] However, the development of infrared and ultraviolet detection technologies faces their own limitations. In the military field, the ultraviolet warning system significantly reduces false alarms due to its unique "sun-blind" characteristics, but it has the disadvantages of low sensitivity and short detection range; although infrared detection technology has the ability to detect at long distances, it is easily affected by external climate and temperature changes, resulting in reduced detection stability. With the rapid progress of modern science and technology, the performance requirements for photoelectric detectors in various fields are increasing, and single-band photoelectric detection technology can no longer meet these needs.

[0005] To sum up, in order to enhance environmental adaptability, multi-scenario application, and exponentially increase the amount of information obtained by the detection system, the development of more advanced dual-color and multi-color detection technology has become one of the important development directions of ultraviolet and infrared photoelectric detection technology. Summary of the invention

[0006] Based on the existing photoelectric detection technology, in conjunction with the semiconductor band structure and material properties that can detect infrared and ultraviolet bands, the present invention proposes a cascaded two-color photoelectric detector that amplifies light signals based on the avalanche effect. The purpose is to overcome the problem of limited wavelength range of light absorption by traditional detectors, to achieve simultaneous detection of ultraviolet and infrared band light signals in the target environment, and to improve the photocurrent gain of infrared band light signal detection.

[0007] To achieve the above object, the present invention provides the following technical solutions:

[0008] Step 1: Prepare a semiconductor heterojunction of an infrared photodetection structure;

[0009] The semiconductor structure for detecting infrared band signals is n-InP / InGaAs / p-InP / p-InGaAs thin film from top to bottom. The InGaAs / InP structure is a mature infrared detector structure. This structure is prepared by epitaxial wafer growth and can achieve the absorption of infrared light near the 1550nm band.

[0010] Step 2: growing an ITO film on the upper surface of the n-InP film on the upper layer of the infrared photodetection structure by magnetron sputtering technology;

[0011] Step 3: Growth of a-Ga on the surface of ITO film by magnetron sputtering technology 2 O 3 film;

[0012] Step 4: Magnetron sputtering technology is used to deposit n-InP film and a-Ga 2 O 3 Ti / Au electrodes were deposited on the film surface.

[0013] After the above steps, the realization of the ultraviolet-infrared cascade two-color photodetector for optical signal amplification based on the avalanche effect is completed. The basic design principle of the present invention is as follows:

[0014] Based on the photovoltaic effect and band theory of semiconductor materials, combined with the structural characteristics of infrared photodetectors and solar-blind ultraviolet avalanche photodetectors, a top-down structure distribution of a-Ga 2 O 3 / ITO / InP / InGaAs semiconductor heterostructure.

[0015] Among them, the ultraviolet band detection structure is a-Ga 2 O 3 / ITO heterojunction: a-Ga 2 O 3 The material has a bandgap of 5.3 eV. The wide bandgap enables the material to absorb light signals near the 254 nm band. 2 O 3 The film contacts with the ITO film to form a semiconductor heterojunction for detecting day-blind ultraviolet band signals, and when the reverse bias voltage applied to both ends of the heterojunction exceeds the critical voltage, the avalanche photoelectric effect of the heterojunction is triggered; ITO material is an important transparent conductive optical material with a high carrier concentration. The high carrier concentration makes the ITO film have good conductivity. At the same time, the ITO material has a band gap of 3.5eV and has a high ultraviolet cut-off ability: based on the material properties, the ITO film participates in the construction of the heterojunction of the day-blind ultraviolet avalanche photodetector in the present invention, and at the same time acts as an infrared detector and a ultraviolet detector in the device. The transition layer between the outer detectors absorbs ultraviolet light and transmits infrared light, effectively preventing ultraviolet light from passing through the upper structure to stimulate the InGaAs / InP semiconductor heterojunction and generate signal crosstalk; the InGaAs / InP detector used to detect infrared band signals is a relatively mature application. Its narrow bandwidth characteristics enable it to have a high detection efficiency in detecting infrared light near the 1100nm-1700nm band, especially the critical 1550nm band, which is basically the only choice at present. At the same time, the infrared detector with InGaAs / InP heterojunction structure has the advantage of being able to work under non-cooling conditions.

[0016] The structure of this photodetector can be regarded as a dual-color photodetector composed of a solar-blind ultraviolet avalanche detector and a PIN infrared photodetector. When the photodetector is working, a reverse bias voltage is applied to both ends of the detector. The reverse bias voltage value is the voltage value that makes the ultraviolet avalanche photodetector enter a critical state. When ultraviolet light is incident, the ultraviolet light is absorbed by the a-Ga 2 O 3 / ITO heterojunction absorption, a-Ga 2 O 3 / ITO heterojunction avalanche effect occurs, InGaAs / InP heterojunction is turned on under the reverse bias of the circuit, and the detector as a whole forms a photocurrent loop; when infrared light is incident, it passes through the wide bandgap material of the upper layer and is absorbed by the InGaAs / InP heterojunction of the lower layer, and the InGaAs / InP heterojunction generates infrared light detection current, and the voltage at both ends changes at the same time. According to the circuit voltage division principle, a-GaAs / InP 2 O 3 / ITO heterojunction increases the reverse bias voltage across the two ends, stimulating a-Ga 2 O 3 / ITO heterojunction undergoes avalanche phenomenon, and the avalanche current increases the loop current, amplifies the infrared signal detection current, and improves the signal gain.

[0017] This invention utilizes the characteristics of avalanche photodetectors that trigger avalanche effects under the conditions of receiving light and increasing reverse bias voltage. During the detection process, the PIN-type infrared photodetector and the day-blind ultraviolet avalanche photodetector are induced to excite each other, effectively improving the gain of the two-color cascade detector.

[0018] In summary, the present invention can realize rapid detection of ultraviolet light and infrared light incident on the detector, and the current signal is significantly amplified by the avalanche gain of the avalanche detector, thereby improving the light detection efficiency.

[0019] The beneficial effects of the present invention are:

[0020] (1) The present invention makes full use of the characteristics of ITO material, which has high light transmittance and low resistivity, and creatively proposes that ITO material be used as a transition layer between infrared photodetectors and day-blind ultraviolet photodetectors, and at the same time as a component of the heterojunction of the day-blind ultraviolet detector and a conductor part of the current loop, thereby realizing the small device integration of infrared detectors and ultraviolet detectors.

[0021] (2) The present invention fully considers the band structure of the material and converts the wide bandgap material a-Ga 2 O 3 Arranged on the upper layer of the device, it realizes the detection and absorption of ultraviolet band signals and prevents ultraviolet light from entering the infrared detection area of ​​the lower layer; the infrared light passes through the upper layer material to reach the lower layer and is absorbed by the narrow bandgap material, thus realizing the simultaneous response to ultraviolet signals and infrared signals.

[0022] (3) When the infrared light excites the InGaAs / InP heterojunction, the present invention generates a small current and reduces the voltage across the infrared photodetector. The voltage across the ultraviolet avalanche photodetector is increased through the principle of circuit voltage division, and an avalanche effect is triggered in the loop. This method effectively improves the current gain of the infrared photodetector and increases the detector's response rate to infrared light signals.

[0023] Therefore, in view of the difficulty of realizing dual-band detection of ultraviolet light and infrared light in the existing methods, the present invention realizes the function of simultaneously detecting signals in the short-wave infrared band and the solar-blind ultraviolet band. 2 O 3 / ITO heterojunctions can excite each other under working conditions by changing the circuit voltage divider. Therefore, compared with ordinary photodetectors, the detector prepared by the present invention has a higher current gain. The detector has good performance under weak light conditions and can be applied in military detection, target reconnaissance, laser radar and other fields. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention will be described in detail below with reference to the accompanying drawings, in which:

[0025] Figure 1 Schematic diagram of the preparation process of the method of the present invention;

[0026] Figure 2 A schematic diagram of the device structure of a cascaded dual-color photodetector for realizing optical signal amplification based on avalanche effect provided in an embodiment of the present invention;

[0027] Reference numerals: 1-n-type InP substrate; 2-InGaAs layer; 3-p-type InP layer; 4-p-type InGaAs layer; 5-Ti / Au electrode; 6-ITO film; 7-a-Ga 2 O 3 Thin film; 8-Ti / Au electrode. DETAILED DESCRIPTION

[0028] This embodiment provides a cascaded two-color photodetector for amplifying optical signals based on the avalanche effect. The detector comprises, from top to bottom, a-Ga 2 O 3 Film, ITO film, n-InP film, i-InGaAs film, p-InP film, p-InGaAs film, Ti / Au electrode. Ti / Au electrodes are grown on the upper surface of a-Ga2O3 film and the surface of p-InGaAs film respectively. Under room temperature, the photodetector is used to receive ultraviolet light and infrared light signals, and wires are drawn out from the Ti / Au electrode to connect the back-end circuit, and the photoelectric signal changes are obtained through signal processing.

[0029] In order to make the method problems solved by the present invention, the method solutions adopted and the method effects achieved more clearly, the present invention is further described in detail below with reference to the accompanying drawings and embodiments.

[0030] A method for preparing a cascaded two-color photodetector for amplifying optical signals based on avalanche effect Figure 1 As shown, the details are as follows:

[0031] Step 1: Prepare a semiconductor heterojunction of an infrared photodetection structure.

[0032] Step 1.1: Perform Zn diffusion treatment on the InP substrate to obtain an n-InP substrate;

[0033] Step 1.2: Deposit an InGaAs layer on the n-InP film with a material thickness of 2 μm;

[0034] Step 1.3: Deposit a p-InP layer on the InGaAs film with a material thickness of 200nm;

[0035] Step 1.4: Deposit a p-InGaAs layer on the p-InP film with a material thickness of 100 nm;

[0036] Step 1.5: Back thinning of the n-InP layer.

[0037] Step 2: Grow an ITO film on the upper surface of the n-InP film on the upper layer of the infrared photodetection structure by magnetron sputtering technology.

[0038] In an environment of high oxygen pressure at an ambient temperature of 200° C., ITO is deposited on the other surface of the n-InP film by a magnetron sputtering method.

[0039] Step 3: Growth of a-Ga on the surface of ITO film by magnetron sputtering technology 2 O 3 film.

[0040] Low-temperature growth of a-Ga by radio frequency magnetron sputtering 2 O 3 The film uses a 99.99% gallium oxide ceramic target as a sputtering source, and a 100×100μm window is photoetched on an ITO substrate. Amorphous gallium oxide is deposited by magnetron sputtering at room temperature. 99.99% high-purity argon and oxygen are introduced into the reaction chamber gas pipeline, Ar:O2=9:1, the sputtering time is 120min, and the thickness is 900nm.

[0041] Step 4: Magnetron sputtering technology is used to deposit n-InP film and a-Ga 2 O 3 Ti / Au electrodes were deposited on the film surface.

[0042] By using DC sputtering technology, the n-InP film surface and a-Ga 2 O 3 Ti / Au electrode was prepared on the film surface, and the electrode size was 20×20 μm.

[0043] The materials for preparing the heterojunction of the present invention are selected from InGaAs, InP, ITO and a-Ga 2 O 3 InGaAs and InP are second generation semiconductor materials and are the preferred materials for making infrared detectors. 2 O 3 It is a third-generation semiconductor material with a bandgap of 5.3eV. It has the characteristics of large bandgap, high electron saturation drift velocity and stable chemical properties. It has significant material performance advantages when used in photoelectric detection devices working in the ultraviolet band and is an ideal material for preparing ultraviolet detectors.

[0044] Reference Figure 2 , Figure 2 Schematic diagram of an infrared-ultraviolet cascade two-color photoelectric detector provided in an embodiment of the present invention, the infrared-ultraviolet cascade two-color photoelectric detector adopts the above-mentioned Figure 1 Specifically, the present invention uses n-InP as a substrate and prepares an infrared detector on its surface; further, an ITO film is grown on the surface of the n-InP film, and the conductive and light-transmitting properties of the ITO film are used to form a current loop, transmit infrared light and absorb ultraviolet light; a-Ga is grown on the surface of the ITO film 2 O 3 The film forms a semiconductor heterojunction with the ITO film, and triggers the photoelectron avalanche effect when absorbing ultraviolet light. The present invention gives the photodetector the ability to simultaneously realize infrared detection and ultraviolet detection, thereby improving the light response and specific detection rate. The wavelengths used for photoelectric detection in the present invention mainly include ultraviolet light and infrared light, with 254nm ultraviolet light and 1550nm infrared light as the main detection bands.

[0045] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the purpose and scope of the technical solution, which should be included in the scope of the claims of the present invention.

Claims

1. A cascaded two-color photodetector for amplifying optical signals based on avalanche effect, characterized in that: The detector shown includes Ga2O3 film, ITO film, InP film, and InGaAs film; the structure from the substrate upward is: n-InGaAs film, p-InP film, InGaAs film, n-InP film, ITO film, and a-Ga2O3 film.

2. A method for preparing a cascaded two-color photodetector for amplifying optical signals based on avalanche effect, characterized in that: The specific steps are as follows: Step 1: Prepare a semiconductor heterojunction for detecting infrared light; Step 2: growing an ITO film on the upper surface of the n-InP film on the upper layer of the infrared photodetection structure by magnetron sputtering technology; Step 3: growing an a-Ga2O3 film on the surface of the ITO film by magnetron sputtering technology; Step 4: Deposit Ti / Au electrodes on the surface of n-InP film and a-Ga2O3 film by magnetron sputtering technology.

3. The method for preparing a cascaded two-color photodetector for realizing optical signal amplification based on avalanche effect according to claim 2, characterized in that: The step 1 is specifically as follows: Step 1.1: Perform Zn diffusion treatment on the InP substrate to obtain an n-InP substrate; Step 1.2: Deposit an InGaAs layer on the n-InP film with a material thickness of 2 μm; Step 1.3: Deposit a p-InP layer on the InGaAs film with a material thickness of 200nm; Step 1.4: Deposit a p-InGaAs layer on the p-InP film with a material thickness of 100 nm; Step 1.5: Back thinning of the n-InP layer.

4. The method for preparing a cascaded two-color photodetector for realizing optical signal amplification based on avalanche effect according to claim 2, characterized in that: In a high oxygen pressure environment, an ITO film is deposited on the other surface of n-InP by magnetron sputtering technology.

5. The method for preparing a cascaded two-color photodetector for realizing optical signal amplification based on avalanche effect according to claim 2, characterized in that: A 99.99% gallium oxide ceramic target was used as a sputtering source, and a-Ga2O3 thin film was grown on an ITO substrate at low temperature by radio frequency magnetron sputtering technology.

6. The method for preparing a cascaded two-color photodetector for realizing optical signal amplification based on avalanche effect according to claim 2, characterized in that: Ti / Au electrodes were prepared on the surface of n-InP film and a-Ga2O3 film respectively by DC magnetron sputtering technology.

Images