An artificial micro-structure integrated InAs-based infrared photodetector

Abstract

The present invention discloses an artificial micro-structure integrated InAs-based infrared photodetector. The detector includes, from bottom to top, an InAs substrate, an InAsSbP blocking layer, an InAs absorption layer, and an InAsSbP window layer; a lower electrode is fabricated on the blocking layer, an upper electrode is fabricated on the window layer, and the artificial micro-structure is fabricated within the upper electrode on the window layer. The key point of the present invention lies in that the provided photodetector has a wide effective detection wavelength coverage range, a high responsivity, a high operating temperature, a low dark current, and can operate at zero bias voltage.

Description

Technical Field

[0001] The present invention relates to the technical field of semiconductor photodetectors, and particularly to an artificial micro-structure integrated InAs-based infrared photodetector. Background Art

[0002] Mid-wave and short-wave infrared photodetection technologies have important applications in many military and civilian fields such as military reconnaissance, infrared imaging guidance, environmental monitoring, intelligent agriculture, and thermophotovoltaics. With the rapid development of science and technology, the application scenarios of infrared photodetection technologies are becoming more and more extensive, and higher requirements are also put forward for the comprehensive performance of detection devices.

[0003] III-V group semiconductor compounds InAs and their alloys have become important materials for fabricating mid-wave and short-wave infrared photodetectors due to advantages such as bandgap matching, high carrier mobility, and the ability to operate at room temperature. However, most of such detectors currently still have defects such as low absorption coefficient, insufficient responsivity, and large dark current, which greatly restrict their practical applications.

[0004] Increasing the responsivity and reducing the dark current are two main means to improve the performance of detectors. In order to fully absorb infrared light, the absorption layer of traditional detectors generally needs to have a certain thickness. In principle, using a thin absorption layer can effectively reduce the dark current. However, a thin absorption layer will result in low quantum efficiency and responsivity. Therefore, the selection of the thickness of the device absorption layer needs to be balanced. In recent years, surface plasmon artificial micro-structures have attracted extensive attention due to their strong light field regulation ability. By introducing surface plasmon artificial micro-structures, the incident light energy can be concentrated and localized in the absorption layer of the material, greatly increasing the absorption efficiency of the absorption layer. Therefore, a thinner absorption layer can be used to obtain high quantum efficiency, and at the same time, the dark current can be reduced, significantly improving the comprehensive performance of the device.

[0005] The present invention discloses an artificial micro-structure integrated InAs infrared photodetector, which has advantages such as a wide effective detection wavelength coverage range, high responsivity, high operating temperature, low dark current, and the ability to operate at zero bias voltage. Summary of the Invention

[0006] (1) Technical Problems to be Solved

[0007] Aiming at the above problems, the present invention discloses an artificial micro-structure integrated InAs infrared photodetector, which is used to at least partially solve problems such as low responsivity, large dark current, and low signal-to-noise ratio of traditional InAs photodetectors.

[0008] (2) Technical Solutions

[0009] The present invention discloses an artificial micro-structure integrated InAs infrared photodetector. The device structure includes a substrate 1, a blocking layer 2, an absorption layer 3, and a window layer 4. A lower electrode 5 is fabricated on the blocking layer, an upper electrode 6 is fabricated on the window layer, and an artificial micro-structure 7 is fabricated on the window layer.

[0010] The substrate 1 is a p-type InAs thin film layer with a (100) crystal orientation.

[0011] The blocking layer 2 is a p-type doped InAs 1-x-y Sb x P y thin film layer.

[0012] The absorption layer 3 is an unintentionally doped InAs thin film layer with a carrier concentration of 3 - 5×10 16 cm -3 , and a thickness of 0.5 - 8 μm.

[0013] The window layer 4 is an n-type doped InAs 1-x-y Sb x P y thin film layer.

[0014] The lower electrode 5 and the upper electrode 6 are composite metal electrodes of Ti and Au with a thickness of 0.05 - 0.5 μm.

[0015] The artificial micro-structure 7 is composed of periodic units with a period of 2.5 - 5 μm. Each unit consists of small squares with a side length of 1 - 2 μm and large squares with a side length of 1.4 - 2.8 μm, made of Au and Ag with a thickness of 0.3 - 0.8 μm.

[0016] The advantages of the present invention are as follows:

[0017] Through the design and fabrication of the artificial micro-structure layer 7, the present invention not only reduces the optical reflection on the surface of the device in the working band, but also localizes the incident light energy by using the surface plasmon mode, greatly improving the responsivity of the device in the working band, suppressing the dark current of the device, and enabling the device to have a high room-temperature responsivity and detectivity. Description of the Drawings

[0018] Figure 1 It is a structural cross-sectional view of the novel artificial micro-structure integrated InAs infrared detector according to the embodiment of the present invention.

[0019] Figure 2 It is a structural top view of the novel artificial micro-structure integrated InAs infrared detector according to the embodiment of the present invention.

[0020] Figure 3 It is a unit structure diagram of the artificial micro-structure of the novel artificial micro-structure integrated InAs infrared detector according to the embodiment of the present invention.

[0021] Figure 4 For the room-temperature zero-bias detectivity of the novel artificial micro-structure integrated InAs infrared detector in the embodiments of the present invention. Specific Embodiments

[0022] To make the objectives, technical solutions and advantages of the present invention more clearly understood, the following further describes the present invention in detail with reference to specific embodiments and the accompanying drawings.

[0023] Embodiment 1: The material of the substrate 1 is p-type InAs material with a (100) crystal orientation. The material of the blocking layer 2 is p-type doped wide-bandgap InAs 1-x-y Sb x P y . The absorption layer 3 is unintentionally doped InAs material with a carrier concentration of 3×10 16 cm -3 , a thickness of 0.5 μm. The window layer 4 is n-type doped wide-bandgap InAs 1-x-y Sb x P y . The lower electrode 5 and the upper electrode 6 are Ti and Au metal electrodes with a thickness of 0.05 μm. The artificial micro-structure 7 is composed of periodic units with a period of 2.5 μm, and each unit is composed of small squares with a side length of 1 μm and large squares with a side length of 1.4 μm made of Au and Ag with a thickness of 0.3 μm.

[0024] Embodiment 2: The material of the substrate 1 is p-type InAs material with a (100) crystal orientation. The material of the blocking layer 2 is p-type doped wide-bandgap InAs 1-x-y Sb x P y . The absorption layer 3 is unintentionally doped InAs material with a carrier concentration of 3×10 16 cm -3 , a thickness of 0.5 μm. The window layer 4 is n-type doped wide-bandgap InAs 1-x-y Sb x P y . The lower electrode 5 and the upper electrode 6 are Ti and Au metal electrodes with a thickness of 0.05 μm. The artificial micro-structure 7 is composed of periodic units with a period of 5 μm, and each unit is composed of small squares with a side length of 2 μm and large squares with a side length of 2.8 μm made of Au and Ag with a thickness of 0.8 μm.

[0025] Embodiment 3: The material of the substrate 1 is p-type InAs material with a (100) crystal orientation. The material of the blocking layer 2 is p-type doped wide-bandgap InAs 1-x-y Sb x P y . The absorption layer 3 is unintentionally doped InAs material with a carrier concentration of 3×1016 cm -3 with a thickness of 0.5 μm, and the window layer 4 is an n-type doped wide-bandgap InAs 1-x-y Sb x P y The lower electrode 5 and the upper electrode 6 are Ti and Au metal electrodes with a thickness of 0.05 μm. The artificial micro-structure (7) is composed of periodic units with a period of 3.25 μm. Each unit consists of small squares with a side length of 1.5 and large squares with a side length of 1.9 μm, made of Au and Ag with a thickness of 0.55 μm.

[0026] The following process is adopted for all three embodiments:

[0027] 1. The blocking layer 2, the absorption layer 3, and the window layer 4 are successively grown in-situ on the InAs substrate by liquid phase epitaxy. An mesa is etched from top to bottom using an etching process. The etching stops at the blocking layer 2, so that for the fabricated device, the exposed parts are the blocking layer 2 and the window layer 4.

[0028] 2. Standard photolithography is used to open electrode holes on the sample surface, and then the lower electrode 5 and the upper electrode 6 are formed by thermal evaporation (other methods such as vacuum sputtering and electron beam evaporation are also applicable).

[0029] 3. Using a registration process, artificial micro-structure holes are opened in the annular region of the upper electrode 6 of the sample, and then Au and Ag are grown by electron beam evaporation to form the artificial micro-structure layer 7.

[0030] The devices fabricated by the three embodiments have similar performance. Under the working conditions of zero bias at room temperature, the responsivity has a significant improvement compared with the unstructured device.

[0031] The above specific embodiments further elaborate on the purpose, technical solutions, and beneficial effects of the present invention. It should be understood that the above are only specific embodiments of the present invention and are not used to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims

1. An artificial micro-structure integrated InAs infrared detector, comprising a substrate (1), a blocking layer (2), an absorption layer (3), and a window layer (4), characterized in that: The structure of the InAs infrared detector from bottom to top is successively a substrate (1), a blocking layer (2), an absorption layer (3), and a window layer (4); a lower electrode (5) is prepared on the blocking layer, and an upper electrode (6) is prepared on the window layer; an artificial microstructure (7) is prepared inside the upper electrode (6) on the window layer (4). The artificial microstructure (7) is composed of periodic units with a period of 2.5 - 5 μm. Each unit consists of small squares with a side length of 1 - 2 μm and large squares with a side length of 1.4 - 2.8 μm, made of Au and Ag with a thickness of 0.3 - 0.8 μm. The manufacturing process steps of the infrared detector are as follows: Using liquid phase epitaxy method, a blocking layer (2), an absorption layer (3), and a window layer (4) are successively grown in-situ on the InAs substrate (1), and mesa is etched from top to bottom using etching process. Etching stops at the blocking layer (2), so that for the fabricated device, the exposed part is the blocking layer (2) and the window layer (4). Using standard photolithography process to open electrode holes on the sample surface, and then using thermal evaporation or vacuum sputtering or electron beam evaporation method to form the lower electrode (5) and the upper electrode (6). Using overlay process, artificial microstructure holes are opened in the annular area of the sample upper electrode (6), and then Au and Ag are grown using electron beam evaporation method to form the artificial microstructure (7).

2. The artificial micro-structure integrated InAs infrared detector according to claim 1, characterized in that, The substrate (1) is a p-type InAs thin film layer with (100) crystal orientation.

3. The artificial micro-structure integrated InAs infrared detector according to claim 1, characterized in that, The absorption layer (3) is an unintentionally doped InAs thin film layer with a carrier concentration of 3 - 5×10 16 cm -3 , and a thickness of 0.5 - 8 μm.

4. The artificial micro-structure integrated InAs infrared detector according to claim 1, characterized in that, The lower electrode (5) and the upper electrode (6) are composite metal electrodes of Ti and Au with a thickness of 0.05 - 0.5 μm.

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