A mid-infrared waveguide integrated detector based on a multi-stage cascade structure
By employing a multi-stage cascaded mid-infrared waveguide integrated detector, the vertical coupling structure is used to achieve effective absorption of incident light, solving the problem that detectors in the prior art cannot simultaneously meet the requirements of high sensitivity and high response speed, and achieving detection effects with both high sensitivity and high response speed.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- HANGZHOU INST FOR ADVANCED STUDY UCAS
- Filing Date
- 2023-04-06
- Publication Date
- 2026-05-29
AI Technical Summary
Existing mid-infrared detectors struggle to achieve both high sensitivity and high response speed simultaneously. Traditional methods, when improving response speed, lead to a decrease in quantum efficiency and detectivity.
The mid-infrared waveguide integrated detector with a multi-stage cascaded structure includes a substrate, a lower cladding layer, a lower waveguide layer, an upper cladding layer, an upper waveguide layer, and a top contact layer. The upper waveguide layer contains an absorption layer with a 2-10 cycle cascaded structure, which achieves effective absorption of incident light through a vertical coupling structure.
This improves the absorption efficiency of the mid-infrared detector and reduces the absorption length, thus providing a detector with high sensitivity and high response speed.
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Figure CN116344658B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of semiconductor technology, and in particular to a mid-infrared waveguide integrated detector based on a multi-stage cascaded structure. Background Technology
[0002] Infrared detection has wide applications in aerospace, industry, medicine, and daily life. In applications such as optical differential detection, dual-comb spectroscopy, and free-space communication, infrared detectors require very high response speeds. The mid-infrared band includes the characteristic absorption spectra of many gases, and mid-infrared detectors can be used for the component detection of various gases and liquids. In optical differential detection methods, the detected beat frequency signal has millions of cycles within 1 second, requiring a very high response speed from the detector. In dual-comb spectroscopy applications, to improve resolution, the repetition frequency of the optical comb needs to be as low as possible, which in the time domain manifests as a short period of the light pulse sequence. This also requires the infrared detector to have the highest possible response speed to effectively detect the pulse signals in the optical comb. The mid-infrared band is a window through the atmosphere, offering high security in free-space optical communication. To achieve mid-infrared optical communication for massive data transmission, high-bandwidth and highly sensitive mid-infrared detectors are also required.
[0003] The response time of a detector is primarily determined by the time it takes for photogenerated carriers to drift or diffuse from their generation to their collection. In traditional mid-infrared detectors, light is incident perpendicularly to the device surface. Improving the response speed involves reducing the thickness of the absorption region, but this leads to a decrease in quantum efficiency and detectivity. However, in waveguide detectors, the light incident direction and the photogenerated carrier motion direction are perpendicular, allowing for a shorter absorption region than in perpendicularly incident detectors, thus resolving the trade-off between response speed and quantum efficiency.
[0004] To improve the response speed of the detector, the absorption region thickness in waveguide integrated detectors is typically several hundred nanometers. To achieve sufficient absorption of incident light, the device length needs to be increased. However, the dark current also increases with the device length, which limits the sensitivity of mid-infrared waveguide detectors. Therefore, there is an urgent need in this field to develop a mid-infrared detector with high sensitivity and high response speed. Summary of the Invention
[0005] The purpose of this invention is to provide a mid-infrared waveguide integrated detector based on a multi-stage cascaded structure to solve the problem that existing detectors cannot simultaneously meet the requirements of high sensitivity and high response speed.
[0006] To achieve the above objectives, the present invention adopts the following technical solution:
[0007] The present invention provides a mid-infrared waveguide integrated detector based on a multi-stage cascaded structure. The mid-infrared waveguide integrated detector includes, from bottom to top, a substrate, a lower cladding layer, a lower waveguide layer, an upper cladding layer, an upper waveguide layer, and a top contact layer; wherein the upper waveguide layer includes an absorption layer with a 2-10 period cascaded structure.
[0008] Preferably, the substrate is an InAs substrate; the thickness of the substrate is 400–600 μm.
[0009] Preferably, the lower cladding layer is made of InAs; the thickness of the lower cladding layer is 1000–2500 nm; and the N-type doping concentration in the lower cladding layer is 1 × 10⁻⁶. 18 ~5×10 18 cm -3 .
[0010] Preferably, the lower waveguide layer is made of GaAs. x Sb 1-x Where x is 0.01 to 0.1; the thickness of the lower waveguide layer is 500 to 2000 nm.
[0011] Preferably, the upper cladding layer is made of InAs; the thickness of the upper cladding layer is 500–1500 nm; and the N-type doping concentration in the upper cladding layer is 1 × 10⁻⁶. 18 ~5×10 18 cm -3 .
[0012] Preferably, the upper waveguide layer includes 2 to 10 cascaded absorption layers with the same period; in the upper waveguide layer, each cascaded absorption layer includes a relaxation region, an absorption region and a tunneling region from bottom to top.
[0013] Preferably, the relaxation region includes 3 to 10 InAs / AlAs regions. x Sb 1-x Quantum wells, where x is 0.1–0.2; in each quantum well, the thickness of InAs is independently 3–10 nm, and the thickness of AlAs is... x Sb 1-x The thickness of the membrane is 1–4 nm; the N-type doping concentration in the relaxation region is 5 × 10⁻⁶. 15 ~2×10 16 cm -3 .
[0014] Preferably, the absorption region comprises 20 to 100 InAs / GaAs cycles. x Sb 1-x A superlattice, where x is 0.01–0.1; in each period of the superlattice, the thickness of InAs is independently 1–3 nm, and the thickness of GaAs is… xSb 1-x The thickness of the absorber is 1–4 nm; the P-type doping concentration in the absorber region is 5 × 10⁻⁶. 15 ~5×10 16 cm -3 .
[0015] Preferably, the tunneling region comprises 2 to 10 GaAs cycles. x Sb 1-x / AlAs x Sb 1-x A superlattice, where x is 0.01–0.2; in each period of the superlattice, GaAs x Sb 1-x The thickness of AlAs is 2-4 nm. x Sb 1-x The thickness of the tunneling region is 1–4 nm; the P-type doping concentration in the tunneling region is 5 × 10⁻⁶. 15 ~2×10 16 cm -3 .
[0016] Preferably, the top contact layer is made of GaAs. x Sb 1-x Where x is 0.01 to 0.1; the thickness of the top contact layer is 10 to 100 nm; and the N-type doping concentration in the top contact layer is 1 × 10⁻⁶. 18 ~5×10 18 cm -3 .
[0017] As can be seen from the above technical solution, compared with the prior art, the beneficial effects of the present invention are as follows:
[0018] The mid-infrared waveguide integrated detector of the present invention includes a multi-level cascaded absorption layer in the upper waveguide layer, which can improve the absorption efficiency of incident light and reduce the absorption length, providing a new method for developing mid-infrared detectors with high sensitivity and high response speed. Attached Figure Description
[0019] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.
[0020] Figure 1 This is a schematic diagram of the mid-infrared waveguide integrated detector of the present invention;
[0021] Figure 2This is a schematic diagram of the absorption layer band structure of the single-period cascaded structure in Example 1;
[0022] Figure 3 This is a schematic diagram of the optical power distribution of the waveguide layer and the absorption layer along the light propagation direction in Example 1. Detailed Implementation
[0023] The present invention provides a mid-infrared waveguide integrated detector based on a multi-stage cascaded structure. The mid-infrared waveguide integrated detector comprises, from bottom to top, a substrate, a lower cladding layer, a lower waveguide layer, an upper cladding layer, an upper waveguide layer, and a top contact layer; wherein the upper waveguide layer comprises an absorption layer with a 2-10 period cascaded structure.
[0024] In this invention, the substrate is preferably an InAs substrate; the refractive index of the InAs substrate is preferably 3 to 3.5, more preferably 3.4 to 3.5; the thickness of the substrate is preferably 400 to 600 μm, more preferably 500 to 550 μm.
[0025] In this invention, the material of the lower cladding layer is preferably InAs; the thickness of the lower cladding layer is preferably 1000–2500 nm, more preferably 1200–2000 nm; in the lower cladding layer, the N-type dopant element is preferably Si, and the N-type doping concentration is preferably 1 × 10⁻⁶. 18 ~5×10 18 cm -3 Further preferred is 2×10 18 ~4×10 18 cm -3 .
[0026] In this invention, the material of the lower waveguide layer is preferably GaAs. x Sb 1-x Further preferred is intrinsic GaAs x Sb 1-x Wherein, x is preferably 0.01 to 0.1, more preferably 0.05 to 0.09; the thickness of the lower waveguide layer is preferably 500 to 2000 nm, more preferably 800 to 1600 nm.
[0027] In this invention, the material of the upper cladding layer is preferably InAs; the thickness of the upper cladding layer is preferably 500–1500 nm, more preferably 600–1200 nm; in the upper cladding layer, the N-type dopant element is preferably Si, and the N-type doping concentration is preferably 1 × 10⁻⁶. 18 ~5×10 18 cm -3 Further preferred is 3×10 18 ~4×10 18 cm -3 .
[0028] In this invention, the upper waveguide layer preferably includes an absorption layer with 2 to 10 identical cascaded structures, and more preferably includes an absorption layer with 3 to 8 identical cascaded structures; in the upper waveguide layer, each cascaded absorption layer includes a relaxation region, an absorption region and a tunneling region sequentially from bottom to top.
[0029] In this invention, the relaxation region preferably includes 3 to 10 InAs / AlAs. x Sb 1-x The quantum well is further preferably composed of 4 to 8 InAs / AlAs atoms. x Sb 1-x Quantum wells, wherein x is preferably 0.1–0.2, more preferably 0.11–0.18; in each quantum well, the thickness of InAs is preferably 3–10 nm, more preferably 4–8 nm, and AlAs... x Sb 1-x The thickness of the independent element is preferably 1–4 nm, more preferably 2–3 nm; in the relaxation region, the N-type doping element is preferably Si, and the N-type doping concentration is preferably 5 × 10⁻⁶. 15 ~2×10 16 cm -3 Further preferred is 6×10 15 ~1×10 16 cm -3 .
[0030] In this invention, the absorption region preferably comprises 20 to 100 InAs / GaAs cycles. x Sb 1-x The superlattice is further preferably composed of 40 to 80 InAs / GaAs periods. x Sb 1-x A superlattice, wherein x is preferably 0.01–0.1, more preferably 0.02–0.08; in each period of the superlattice, the thickness of InAs is independently preferably 1–3 nm, more preferably 2–2.5 nm, and GaAs… x Sb 1-x The thickness of the absorption region is preferably 1–4 nm, more preferably 2–3 nm; in the absorption region, the P-type doping element is preferably Be, and the P-type doping concentration is preferably 5 × 10⁻⁶. 15 ~5×10 16 cm -3 Further preferred is 6×10 15 ~4×10 16 cm -3 .
[0031] In this invention, the tunneling region preferably comprises 2 to 10 GaAs cycles.x Sb 1-x / AlAs x Sb 1-x The superlattice is further preferably composed of 3 to 9 GaAs periods. x Sb 1-x / AlAs x Sb 1-x A superlattice, wherein x is preferably 0.01–0.2, more preferably 0.09–0.16; in each period of the superlattice, GaAs x Sb 1-x The thickness is preferably 2-4 nm, more preferably 3-3.5 nm, AlAs x Sb 1-x The thickness of the tunneling region is preferably 1–4 nm, more preferably 2–3 nm; in the tunneling region, the P-type doping element is preferably Be, and the P-type doping concentration is preferably 5 × 10⁻⁶. 15 ~2×10 16 cm -3 Further preferred is 6×10 15 ~1×10 16 cm -3 .
[0032] In this invention, the material of the top contact layer is preferably GaAs. x Sb 1-x Wherein, x is preferably 0.01 to 0.1, more preferably 0.02 to 0.09; the thickness of the top contact layer is preferably 10 to 100 nm, more preferably 20 to 80 nm; in the top contact layer, the N-type doping element is preferably Si, and the N-type doping concentration is preferably 1 × 10⁻⁶. 18 ~5×10 18 cm -3 Further preferred is 3×10 18 ~4×10 18 cm -3 .
[0033] In this invention, the refractive index of the InAs is preferably 3 to 3.5, more preferably 3.4 to 3.5; the GaAs x Sb 1-x The refractive index is preferably 3.3 to 3.8, more preferably 3.5 to 3.7; the AlAs x Sb 1-x The refractive index is preferably 3 to 3.5, and more preferably 3.1 to 3.3.
[0034] The mid-infrared waveguide integrated detector of the present invention adopts a vertical coupling structure of two waveguides. Light is incident from the lower waveguide layer and enters the upper waveguide layer through vertical coupling. The upper waveguide layer contains a multi-level cascaded absorption layer, which can effectively absorb the incident light and reduce the absorption length, thereby obtaining a mid-infrared waveguide integrated detector with high sensitivity and high response speed.
[0035] The technical solutions provided by the present invention will be described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.
[0036] In this embodiment, the mid-infrared waveguide integrated detector comprises, from bottom to top: a substrate, a lower cladding layer, a lower waveguide layer, an upper cladding layer, an upper waveguide layer, and a top contact layer.
[0037] Example 1
[0038] The substrate is an InAs substrate with a thickness of 500 μm;
[0039] The lower cladding layer is made of InAs material with a thickness of 2000 nm, and the N-type dopant is Si with an N-type doping concentration of 2 × 10⁻⁶. 18 cm -3 ;
[0040] The lower waveguide layer is intrinsic GaAs. 0.09 Sb 0.91 The thickness is 700nm;
[0041] The upper cladding layer is made of InAs material with a thickness of 500 nm, and the N-type dopant is Si with an N-type doping concentration of 2 × 10⁻⁶. 18 cm -3 ;
[0042] The upper waveguide layer comprises a four-period cascaded absorption layer. Each cascaded absorption layer consists of, from bottom to top, a relaxation region, an absorption region, and a tunneling region. The relaxation region includes seven InAs / AlAs atoms. 0.16 Sb 0.84 The quantum well contains InAs layers with thicknesses of 7.8 nm, 6.5 nm, 5.6 nm, 4.9 nm, 4.4 nm, 4 nm, and 3.6 nm from bottom to top. The AlAs layers are... 0.16 Sb 0.84 The thickness of each element is 1.2 nm, the N-type dopant is Si, and the N-type doping concentration is 5 × 10⁻⁶. 15 cm -3 The absorption region structure is a 50-period InAs / GaAs. 0.09 Sb 0.91 The superlattice consists of InAs with a thickness of 2.1 nm and GaAs with a thickness of 2.1 nm per period. 0.09 Sb 0.91The composition is as follows: the P-type dopant is Be, and the P-type doping concentration is 5 × 10⁻⁶. 15 cm -3 The tunneling region structure is a 6-period GaAs 0.09 Sb 0.91 / AlAs 0.16 Sb 0.84 Superlattice, each period of the superlattice consists of GaAs with a thickness of 2.1 nm. 0.09 Sb 0.91 And AlAs with a thickness of 1.2 nm 0.16 Sb 0.84 The composition is as follows: the P-type dopant is Be, and the P-type doping concentration is 5 × 10⁻⁶. 15 cm -3 ;
[0043] The top contact layer is GaAs 0.09 Sb 0.91 The material has a thickness of 30 nm, and the p-type dopant is Be with a p-type doping concentration of 1 × 10⁻⁶. 18 cm -3 .
[0044] The mid-infrared waveguide integrated detector described in this embodiment uses GaAs with a refractive index of 3.7. 0.09 Sb 0.91 Material: AlAs with a refractive index of 3.3 0.16 Sb 0.84 And InAs with a refractive index of 3.5.
[0045] The working process of the mid-infrared waveguide integrated detector is as follows: light enters from the lower waveguide layer, enters the upper waveguide layer through vertical coupling, and is absorbed by the absorption layer in the upper waveguide layer.
[0046] The optical power of the waveguide layer and the absorption layer along the light propagation direction in this embodiment was measured, and the results are as follows: Figure 3 As shown. By Figure 3 It can be seen that the absorption layer in the upper waveguide layer can achieve complete absorption of light, with an absorption length of 40μm.
[0047] Example 2
[0048] The substrate is an InAs substrate with a thickness of 500 μm;
[0049] The lower cladding layer is made of InAs material with a thickness of 2000 nm, and the N-type dopant is Si with an N-type doping concentration of 2 × 10⁻⁶. 18 cm -3 ;
[0050] The lower waveguide layer is intrinsic GaAs. 0.09 Sb 0.91 The thickness is 900nm;
[0051] The upper cladding layer is made of InAs material with a thickness of 650 nm, and the N-type dopant is Si with an N-type doping concentration of 2 × 10⁻⁶. 18 cm -3 ;
[0052] The upper waveguide layer comprises a 7-period cascaded absorption layer. Each cascaded absorption layer consists of, from bottom to top, a relaxation region, an absorption region, and a tunneling region. The relaxation region consists of 7 InAs / AlAs structures. 0.16 Sb 0.84 The quantum well contains InAs layers with thicknesses from bottom to top of 7.9 nm, 6.6 nm, 5.7 nm, 5 nm, 4.5 nm, 4.1 nm, and 3.7 nm, and AlAs layers respectively. 0.16 Sb 0.84 The thickness of each element is 1.2 nm, the N-type dopant is Si, and the N-type doping concentration is 5 × 10⁻⁶. 15 cm -3 The absorption region structure is a 52-period InAs / GaAs. 0.09 Sb 0.91 The superlattice consists of InAs with a thickness of 2.85 nm and GaAs with a thickness of 2.1 nm per period. 0.09 Sb 0.91 The composition is as follows: the P-type dopant is Be, and the P-type doping concentration is 5 × 10⁻⁶. 15 cm -3 The tunneling region structure is a 6-period GaAs 0.09 Sb 0.91 / AlAs 0.16 Sb 0.84 Superlattice, each period of the superlattice consists of GaAs with a thickness of 2.1 nm. 0.09 Sb 0.91 And AlAs with a thickness of 1.2 nm 0.16 Sb 0.84 The composition is as follows: the P-type dopant is Be, and the P-type doping concentration is 5 × 10⁻⁶. 15 cm -3 ;
[0053] The top contact layer is GaAs 0.09 Sb 0.91 The material has a thickness of 30 nm, and the p-type dopant is Be with a p-type doping concentration of 1 × 10⁻⁶. 18 cm -3 .
[0054] The mid-infrared waveguide integrated detector described in this embodiment uses GaAs with a refractive index of 3.7. 0.09 Sb 0.91 Material: AlAs with a refractive index of 3.3 0.16 Sb 0.84And InAs material with a refractive index of 3.5.
[0055] The working process of the mid-infrared waveguide integrated detector is as follows: light enters from the lower waveguide layer, enters the upper waveguide layer through vertical coupling, and is absorbed by the absorption layer in the upper waveguide layer.
[0056] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.
Claims
1. A mid-infrared waveguide integrated detector based on a multi-stage cascaded structure, characterized in that, The mid-infrared waveguide integrated detector comprises, from bottom to top, a substrate, a lower cladding layer, a lower waveguide layer, an upper cladding layer, an upper waveguide layer, and a top contact layer; wherein the upper waveguide layer comprises an absorption layer with a 2-10 periodic cascaded structure. The lower cladding layer is made of InAs; the N-type doping concentration in the lower cladding layer is 1×10⁻⁶. 18 ~5×10 18 cm -3 ; The lower waveguide layer is made of GaAs. x Sb 1-x Where x is 0.01 to 0.1; The upper cladding layer is made of InAs; the N-type doping concentration in the upper cladding layer is 1×10⁻⁶. 18 ~5×10 18 cm -3 ; In the upper waveguide layer, each periodically cascaded absorption layer includes, from bottom to top, a relaxation region, an absorption region, and a tunneling region. The relaxation region includes 3 to 10 InAs / AlAs. x Sb 1-x A quantum well, wherein x is 0.1 to 0.2; the N-type doping concentration in the relaxation region is 5 × 10⁻⁶. 15 ~2×10 16 cm -3 ; The absorption region comprises 20–100 InAs / GaAs cycles. x Sb 1-x A superlattice, wherein x is 0.01 to 0.1; the p-type doping concentration in the absorption region is 5 × 10⁻⁶. 15 ~5×10 16 cm -3 ; The tunneling region includes 2 to 10 GaAs cycles. x Sb 1-x / AlAs x Sb 1-x A superlattice, wherein x is 0.01–0.2; the P-type doping concentration in the tunneling region is 5 × 10⁻⁶. 15 ~2×10 16 cm -3 ; The top contact layer is made of GaAs. x Sb 1-x Where x is 0.01 to 0.1; the N-type doping concentration in the top contact layer is 1 × 10⁻⁶. 18 ~5×10 18 cm -3 .
2. The mid-infrared waveguide integrated detector based on a multi-stage cascaded structure according to claim 1, characterized in that, The substrate is an InAs substrate; the thickness of the substrate is 400–600 μm.
3. The mid-infrared waveguide integrated detector based on a multi-stage cascaded structure according to claim 2, characterized in that, The thickness of the lower cladding layer is 1000–2500 nm.
4. The mid-infrared waveguide integrated detector based on a multi-stage cascaded structure according to any one of claims 1 to 3, characterized in that, The thickness of the lower waveguide layer is 500–2000 nm.
5. The mid-infrared waveguide integrated detector based on a multi-stage cascaded structure according to claim 4, characterized in that, The thickness of the upper cladding layer is 500–1500 nm.
6. The mid-infrared waveguide integrated detector based on a multi-stage cascaded structure according to claim 1, 2, 3, or 5, characterized in that, The upper waveguide layer includes an absorption layer with 2 to 10 identical cascaded periods.
7. The mid-infrared waveguide integrated detector based on a multi-stage cascaded structure according to claim 6, characterized in that, In each quantum well of the relaxation region, the thickness of InAs is independently 3–10 nm, and the thickness of AlAs is… x Sb 1-x The thickness is 1–4 nm.
8. The mid-infrared waveguide integrated detector based on a multi-stage cascaded structure according to claim 7, characterized in that, In each period of the superlattice of the absorption region, the thickness of InAs is independently 1–3 nm, and that of GaAs is… x Sb 1-x The thickness is 1–4 nm.
9. The mid-infrared waveguide integrated detector based on a multi-stage cascaded structure according to claim 7 or 8, characterized in that, In each periodic superlattice of the tunneling region, GaAs x Sb 1-x The thickness of AlAs is 2-4 nm. x Sb 1-x The thickness is 1–4 nm.
10. The mid-infrared waveguide integrated detector based on a multi-stage cascaded structure according to claim 1, characterized in that, The thickness of the top contact layer is 10–100 nm.