Germanium photoelectric detector with adjustable detection wavelength

Abstract

The invention provides a germanium photoelectric detector with an adjustable detection wavelength, and belongs to the technical field of photoelectric sensors. The germanium photoelectric detector comprises a germanium detector layer which comprises a substrate layer, a PIN structure layer and a germanium absorption layer which are stacked in sequence, and the germanium absorption layer is located above an intrinsic region of the PIN structure layer; the isolation layer is formed above the germanium detector layer, a groove and two first electrode through holes are formed in the isolation layer, the groove is located above the germanium absorption layer, the groove and the germanium absorption layer are arranged in a spaced mode, the groove comprises a resistor cavity and two second electrode through holes which are isolated from each other, and the bottoms of the second electrode through holes are communicated with the resistor cavity; the two working electrode layers are respectively formed in the two first electrode through holes; the heat adjusting resistance layer is arranged in the resistance concave cavity; the two thermal adjusting electrode layers are respectively formed in the two second electrode through holes; and the thermal regulation circuit is connected with the two thermal regulation electrode layers and is used for providing thermal regulation voltage for the thermal regulation resistance layer. According to the invention, the detection wavelength range of the detector can be expanded in a simple mode.

Description

Technical Field

[0001] This application relates to the field of photoelectric sensor technology, and in particular to a germanium photodetector with tunable detection wavelength. Background Technology

[0002] In recent years, as traditional microelectronics has gradually approached the limits of Moore's Law, the integrated circuit field faces serious problems such as energy consumption and cost. This has led to a gradual shift from integrated circuits to integrated optical paths. Optical communication, with its unique method of information transmission, can effectively solve some of the dilemmas faced by integrated circuits and is already widely used in short-range communication. Meanwhile, detectors, as the core devices for photoelectric conversion, are also constantly evolving towards larger detection ranges, higher speeds, lower dark currents, and higher responsivity as various fields demand higher transmission speeds.

[0003] Currently, whether for academic research or for the market, most germanium detectors operate in the O-band (1260-1360nm) and C-band (1530-1565nm), and their responsivity can generally reach 1 A / W. However, for longer wavelengths, due to the limitations of the germanium bandgap, the responsivity will decrease sharply, only maintaining at 0.1 A / W-0.3 A / W.

[0004] Therefore, to meet the need for a wider detection range, various research institutes and companies have sought numerous solutions, such as introducing stress or doping germanium with other elements, such as tin, all aimed at altering the bandgap of germanium. However, these methods all face serious process implementation challenges. For example, changing the bandgap by applying stress requires etching trenches as deep as possible around the material, which increases the difficulty of the process. Summary of the Invention

[0005] One object of the present invention is to provide a germanium photodetector with adjustable detection wavelength, which can extend the detection wavelength range of the detector in a simple manner.

[0006] Another objective of this invention is to maintain compatibility of the preparation process.

[0007] A further objective of the present invention is to improve heat transfer efficiency while avoiding affecting the operation of the working electrode layer.

[0008] An embodiment of the present invention provides a germanium photodetector with tunable detection wavelength, comprising:

[0009] A germanium detector layer includes a substrate layer, a PIN structure layer, and a germanium absorption layer stacked sequentially, wherein the germanium absorption layer is located above the intrinsic region of the PIN structure layer;

[0010] An isolation layer is formed above the germanium detector layer. The isolation layer has a groove and two first electrode vias. The groove is located above the germanium absorption layer and is spaced apart from the germanium absorption layer. The groove includes a resistor cavity and two mutually isolated second electrode vias whose bottoms are connected to the resistor cavity.

[0011] Two working electrode layers are respectively formed in the two first electrode through holes;

[0012] A thermally adjustable resistor layer is disposed within the resistor cavity;

[0013] Two thermally adjustable electrode layers are respectively formed in the two second electrode vias;

[0014] A thermally adjustable circuit, connected to the two thermally adjustable electrode layers, is used to provide a thermally adjustable voltage to the thermally adjustable resistor layer.

[0015] Furthermore, the two working electrode layers are formed by two depositions, and the thermally adjustable resistor layer and the two thermally adjustable electrode layers are formed simultaneously during the second deposition of the two working electrode layers.

[0016] Furthermore, a heat-conducting layer is formed on the bottom wall of the resistive cavity.

[0017] Furthermore, the two sidewalls of the resistor cavity are arranged opposite to each other, and the two sidewalls are respectively spaced apart from the two working electrode layers, and a heat insulation layer is formed at the two sidewalls.

[0018] Furthermore, the orthogonal projection of the germanium absorption region onto the thermally adjustable resistive layer is located within the thermally adjustable resistive layer.

[0019] Furthermore, the orthogonal projection of the germanium absorption region onto the intrinsic region lies within the intrinsic region.

[0020] Furthermore, the material of the thermally adjustable resistive layer is titanium nitride, tantalum nitride, chromium nitride, titanium carbide, silicon carbide, or aluminum oxide.

[0021] Furthermore, the thickness of the germanium absorber layer is any value between 300nm and 400nm, the thickness of the thermally adjustable resistive layer is any value between 100nm and 150nm, the distance between the thermally adjustable resistive layer and the germanium absorber layer is any value between 2μm and 2.3μm, and the sheet resistance of the thermally adjustable resistive layer is 10Ω / □ -15Ω / □ Any value in the range.

[0022] Furthermore, the thermal adjustment voltage is any value between 2V and 4.5V.

[0023] Furthermore, the thermal adjustment voltage is any value between 2.8V and 3.2V.

[0024] According to a first aspect of the present invention, a germanium photodetector including a thermally adjustable resistive layer is provided. By applying different magnitudes of thermally adjustable voltages across the thermally adjustable resistive layer through a thermally adjustable circuit, the thermally adjustable resistive layer can generate different amounts of heat, thereby causing the germanium absorption layer to reach different temperatures. By changing the temperature of the germanium absorption layer, the band gap of the germanium material can be altered, thereby expanding the detection wavelength range of the detector. In other words, this application can expand the detection wavelength range of the detector through the simple method of setting a thermally adjustable resistive layer and a thermally adjustable circuit.

[0025] Furthermore, this method of depositing the working electrode layer, the thermally tunable resistor layer, and the thermally tunable electrode layer in two stages can utilize the existing LPIN (horizontal trench detector) process, thus maintaining the compatibility of the fabrication process, thereby reducing the fabrication difficulty and saving fabrication costs.

[0026] According to a second aspect of the present invention, by providing a heat-conducting layer at the bottom of the resistor cavity, the heat of the thermally adjustable resistor layer can be transferred to the germanium absorption layer more efficiently, thereby increasing the thermal conductivity. By providing a heat-insulating layer on the sidewall of the resistor cavity, the heat of the thermally adjustable resistor layer can be prevented from being transferred to the working electrode layer from both sides, preventing heat from spreading to unnecessary areas, thereby improving the heat transfer efficiency while avoiding affecting the operation of the working electrode layer. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of a germanium photodetector according to an embodiment of the present invention;

[0028] Figure 2 The cross-sectional temperature distribution of the germanium absorption layer of the germanium photodetector in Example 1 is shown when the thermally adjustable voltages are 1V, 2V, 3V and 4V.

[0029] Figure 3 This is a DC characteristic curve of the dark current as a function of bias voltage when the thermally adjustable voltage of the germanium photodetector in Example 1 is increased from 0.5V to 4.5V in increments of 0.5V.

[0030] Figure 4 The graph shows the DC characteristic curve of the photocurrent as a function of the bias voltage when the thermally adjustable voltage of the germanium photodetector in Example 1 is increased from 0.5V to 4.5V in increments.

[0031] Figure 5 This is a DC characteristic curve of the responsivity of the germanium photodetector in Example 1 as the thermally adjustable voltage increases from 0.5V to 4.5V in increments.

[0032] Figure 6This is a DC characteristic curve of the dark current of the germanium photodetector in Example 1 when the bias voltage is -1V, -2V and -3V, as a function of the hot-tuning voltage.

[0033] Figure 7 This is a DC characteristic curve of the photocurrent as a function of the hot-tuning voltage for the germanium photodetector of Example 1 with bias voltages of -1V, -2V and -3V.

[0034] Figure 8 This is a DC characteristic curve of the responsivity of the germanium photodetector in Example 1 when the bias voltage is -1V, -2V and -3V, as a function of the thermally modulated voltage.

[0035] Figure 9 The graphs show the DC characteristics of the photocurrent as a function of bias voltage for incident light at 1550 nm under heated and unheated conditions in Examples 1, 2, 3 and 4.

[0036] Figure 10 The graphs show the DC characteristics of the photocurrent as a function of bias voltage for incident light at 1600 nm under heated and unheated conditions in Examples 1 and 2.

[0037] Figure 11 The graphs show the DC characteristics of the photocurrent as a function of bias voltage for incident light at 1630 nm under heated and unheated conditions in Examples 1 and 2.

[0038] Figure 12 The DC characteristic curves of the responsivity of 1550nm incident light under heated and unheated conditions are shown for Examples 1, 2, 3 and 4.

[0039] Figure 13 The graphs show the DC characteristics of the responsivity of 1600nm incident light under heated and unheated conditions in Examples 1 and 2 as a function of bias voltage.

[0040] Figure 14 The graphs show the DC characteristics of the responsivity of 1630nm incident light under heated and unheated conditions in Examples 1 and 2 as a function of bias voltage.

[0041] Figure 15 The following are the frequency response curves of the germanium photodetector of Example 1 under heated and unheated conditions with bias voltages of -2V and -4V, respectively;

[0042] Figure 16 The frequency response curves of the germanium photodetector in Example 2 under heated and unheated conditions with bias voltages of -2V and -4V, respectively.

[0043] Figure label:

[0044] 100-Geronium photodetector, 10-Geronium detector layer, 11-Substrate layer, 12-PIN structure layer, 13-Geronium absorber layer, 111-Silicon dioxide buried oxide layer, 112-Top silicon layer, 121-Heavily doped P-type region, 122-Lightly doped P-type region, 123-Intrinsic region, 124-Lightly doped N-type region, 125-Heavily doped N-type region, 20-Isolation layer, 21-Groove, 22-First electrode via, 30-Working electrode layer, 40-Thermo-tunable resistor layer, 50-Thermo-tunable electrode layer. Detailed Implementation

[0045] To make the above-mentioned objectives, features, and advantages of this application more apparent and understandable, the specific embodiments of this application are described in detail below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a thorough understanding of this application. However, this application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of this application. Therefore, this application is not limited to the specific embodiments disclosed below.

[0046] It should be noted that when a component is referred to as being "fixed to" or "set on" another component, it can be directly on the other component or there may be an intermediate component. When a component is considered to be "connected to" another component, it can be directly connected to the other component or there may be an intermediate component present. The terms "vertical," "horizontal," "upper," "lower," "left," "right," and similar expressions used in this application's specification are for illustrative purposes only and do not represent the only possible implementation.

[0047] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0048] In this application, unless otherwise expressly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature and the second feature are in indirect contact through an intermediate medium. Furthermore, "above," "over," and "on top" the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0049] Unless otherwise defined, all technical and scientific terms used in this application have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used in this application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. The term "and / or" as used in this application includes any and all combinations of one or more of the associated listed items.

[0050] Figure 1 This is a schematic diagram of the structure of a germanium photodetector 100 according to an embodiment of the present invention. Figure 1 As shown, in one embodiment, the germanium photodetector 100 includes a germanium detector layer 10, an isolation layer 20, two working electrode layers 30, a thermally adjustable resistor layer 40, two thermally adjustable electrode layers 50, and a thermally adjustable circuit (not shown). The germanium detector layer 10 includes a substrate layer 11, a PIN structure layer 12, and a germanium absorber layer 13 stacked sequentially. Generally, the substrate layer 11 includes a silicon dioxide buried oxide layer 111 and a top silicon layer 112, which can be fabricated using SOI wafer processing. The PIN structure layer 12 generally includes a heavily doped P-type region 121, a lightly doped P-type region 122, an intrinsic region 123, a lightly doped N-type region 124, and a heavily doped N-type region 125 arranged sequentially along a horizontal direction. The heavily doped P-type region 121 and the heavily doped N-type region 125 are heavily doped ohmic contact regions used to connect to the two working electrode layers 30, respectively. The various regions of the PIN structure layer 12 can be formed by ion implantation after material is deposited on the top silicon layer 112. The germanium absorber layer 13 is located above the intrinsic region 123 of the PIN structure layer 12. An isolation layer 20 is formed above the germanium detector layer 10. The isolation layer 20 can be made of silicon dioxide and formed by deposition. The isolation layer 20 has a groove 21 and two first electrode vias 22. The groove 21 is located above the germanium absorber layer 13 and spaced apart from it. The groove 21 includes a resistor cavity and two mutually isolated second electrode vias whose bottoms are connected to the resistor cavity. The bottoms of the two first electrode vias 22 are respectively connected to a heavily doped P-type region 121 and a heavily doped N-type region 125. Two working electrode layers 30 are formed within the two first electrode vias 22. The working electrode layers 30 can be made of commonly used conductive materials such as aluminum or copper. A thermally adjustable resistor layer 40 is disposed within the resistor cavity. The thermally adjustable resistor layer 40 can be formed by deposition using silicon nitride, tantalum nitride, chromium nitride, titanium carbide, silicon carbide, or aluminum oxide. Two heat-adjustable electrode layers 50 are formed in two second electrode vias, respectively. The material of the heat-adjustable electrode layers 50 can be common conductive materials such as aluminum or copper. The heat-adjustable circuit is connected to the two heat-adjustable electrode layers 50 and is used to provide heat-adjustable voltage to the heat-adjustable resistor layer 40. Of course, the heat-adjustable circuit can also be configured to be in a non-use state where no heat-adjustable voltage is applied across the heat-adjustable resistor layer 40.

[0051] This application provides a germanium photodetector 100 including a thermally adjustable resistive layer 40. By applying different thermally adjustable voltages across the thermally adjustable resistive layer 40 through a thermally adjustable circuit, the thermally adjustable resistive layer 40 can generate different amounts of heat, thereby causing the germanium absorption layer 13 to reach different temperatures. By changing the temperature of the germanium absorption layer 13, the band gap of the germanium material can be changed, thereby expanding the detection wavelength range of the detector. In other words, this application can expand the detection wavelength range of the detector through the simple method of setting a thermally adjustable resistive layer 40 and a thermally adjustable circuit.

[0052] In a further embodiment, the two working electrode layers 30 are formed through two deposition processes, with the thermally adjustable resistor layer 40 and the two thermally adjustable electrode layers 50 formed simultaneously during the second deposition of the two working electrode layers 30. Specifically, during the first deposition, a working electrode layer 30 of a first height is formed within the two second electrode vias. During the second deposition, the thermally adjustable resistor layer 40 is deposited in the groove 21, and then the thermally adjustable electrode layers 50 are deposited within the two first electrode vias 22. Simultaneously with the deposition of the thermally adjustable resistor layer 40 and the thermally adjustable electrode layers 50, a working electrode layer 30 of a second height continues to be formed within the two second electrode vias. It should be noted that the first and second depositions mentioned here are defined by time, not by the different deposition materials.

[0053] This method of depositing the working electrode layer 30, the thermally tunable resistor layer 40, and the thermally tunable electrode layer 50 in two stages can utilize the existing LPIN (horizontal trench detector) process, thus maintaining compatibility with the fabrication process, thereby reducing fabrication difficulty and saving fabrication costs.

[0054] In a further embodiment, the orthographic projection of the germanium absorption region onto the thermally adjustable resistive layer 40 lies within the thermally adjustable resistive layer 40. The orthographic projection of the germanium absorption region onto the intrinsic region 123 lies within the intrinsic region 123. Preferably, the thermally adjustable resistive layer 40, the germanium absorption layer 13, and the intrinsic region 123 are vertically aligned.

[0055] Setting the area of ​​the thermally tunable resistive layer 40 to be larger than that of the germanium absorption region allows the heat from the thermally tunable resistive layer 40 to be transferred to the germanium absorption region more effectively. Setting the area of ​​the germanium absorption region to be smaller than that of the intrinsic region 123 can improve the light absorption efficiency, reduce parasitic capacitance and dark current, thereby improving the response speed.

[0056] In another embodiment, a heat-conducting layer is formed on the bottom wall of the resistor cavity. The material of the heat-conducting layer can be copper, aluminum, gold, or a high thermal conductivity ceramic material. Two opposite sidewalls of the resistor cavity are arranged at intervals from the two working electrode layers 30. A heat-insulating layer is formed on the two sidewalls. The material of the heat-insulating layer can be silicon dioxide, titanium dioxide, alumina, or other materials.

[0057] In the above scheme, by setting a heat-conducting layer at the bottom of the resistor cavity, the heat of the thermally adjustable resistor layer 40 can be transferred to the germanium absorption layer 13 more efficiently, increasing the thermal conductivity. Setting a heat-insulating layer on the side wall of the resistor cavity can prevent the heat of the thermally adjustable resistor layer 40 from being transferred to the working electrode layer 30 from both sides, preventing the heat from spreading to unnecessary areas, thus improving the heat transfer efficiency while avoiding affecting the operation of the working electrode layer 30.

[0058] In one embodiment, the thickness of the germanium absorber layer 13 is 300 nm, 320 nm, 350 nm, 380 nm, or 400 nm, or any other value between 300 nm and 400 nm. The thickness of the thermally adjustable resistive layer 40 is 100 nm, 120 nm, 130 nm, 140 nm, or 150 nm, or any other value between 100 nm and 150 nm. The distance between the thermally adjustable resistive layer 40 and the germanium absorber layer 13 is 2 μm, 2.1 μm, 2.2 μm, or 2.3 μm, or any other value between 2 μm and 2.3 μm. The sheet resistance of the thermally adjustable resistive layer 40 is 10 Ω / □ 12Ω / □ 13Ω / □ 14Ω / □ Or 15Ω / □ It can also be 10Ω / □ -15Ω / □ Any other value in the range. When it is necessary to extend the detector's detection wavelength to the L-band, the thermal adjustment circuit provides a thermal adjustment voltage of any value from 2V to 4.5V, such as 2V, 3V, 4V, or 4.5V, or any other value from 2V to 4.5V. To maintain good responsivity and dark current, the thermal adjustment voltage is any value from 2.8V to 3.2V, such as 2.8V, 3V, or 3.2V, or any other value from 2.8V to 3.2V.

[0059] Example 1

[0060] The silicon dioxide buried oxide layer 111 has a thickness of 2 / 3 μm, the top silicon layer 112 has a thickness of 220 nm, the PIN structure layer 12 has a thickness of 0.2 μm, the intrinsic region 123 has a width of 0.6 μm and a length of 10 μm, the germanium absorber layer 13 has a thickness of 350 nm, a length of 10 μm and a width of 0.5 μm, the thermally tunable resistor layer 40 is made of titanium nitride and has a thickness of 120 nm, a length of 12 μm and a width of 1 μm, the distance between the germanium absorber layer 13 and the thermally tunable resistor layer 40 is 2.1 μm, and the working electrode layer 30 and the thermally tunable electrode layer 50 are both made of aluminum.

[0061] Example 2

[0062] The only difference between Example 2 and Example 1 is that the length of the germanium absorption layer 13 is 20 μm, the length of the intrinsic region 123 is 20 μm, and the length of the thermally tunable resistive layer 40 is 22 μm.

[0063] Example 3

[0064] The only difference between Example 3 and Example 1 is that the length of the germanium absorption layer 13 is 30 μm, the length of the intrinsic region 123 is 30 μm, and the length of the thermally tunable resistive layer 40 is 32 μm.

[0065] Example 4

[0066] The only difference between Example 4 and Example 1 is that the length of the germanium absorption layer 13 is 40 μm, the length of the intrinsic region 123 is 40 μm, and the length of the thermally tunable resistive layer 40 is 42 μm.

[0067] Figure 2 The diagram shows the cross-sectional temperature distribution of the germanium absorption layer 13 when the thermally adjustable voltages of the germanium photodetector 100 of Example 1 are 1V, 2V, 3V and 4V. Figure 2 The heat-tuning voltages in (a), (b), (c), and (d) are 1V, 2V, 3V, and 4V, respectively, corresponding to powers of 15mW, 60mW, 135mW, and 240mW. The average temperatures of the germanium absorption layer 13 are 301K, 328K, 373K, and 435K, respectively, with corresponding band gaps of 0.8eV, 0.788eV, 0.765eV, and 0.734eV. The theoretical maximum detection wavelengths are 1550nm, 1573nm, 1620nm, and 1689nm, respectively. Therefore, when the heat-tuning voltage is less than 2V, the detection wavelength of the germanium photodetector 100 cannot be extended to the L-band, or even changes almost no band. Only when the heat-tuning voltage is greater than or equal to 2V does the heat-tuning effect show a significant improvement.

[0068] Figure 3 This is a DC characteristic curve of the dark current as a function of bias voltage when the thermally adjustable voltage of the germanium photodetector 100 in Example 1 is increased from 0.5V to 4.5V in increments. Figure 3 The horizontal axis represents the bias voltage (in V), and the vertical axis represents the dark current (in A).

[0069] Figure 4 The graph shows the DC characteristic curve of the photocurrent as a function of the bias voltage when the thermally adjustable voltage of the germanium photodetector 100 in Example 1 is increased from 0.5V to 4.5V in increments. Figure 4 The horizontal axis represents the bias voltage (in V), and the vertical axis represents the photocurrent (in A).

[0070] Figure 5This is a DC characteristic curve of the responsivity of the germanium photodetector 100 in Example 1 as the thermally adjustable voltage increases from 0.5V to 4.5V in increments. Figure 5 The horizontal axis represents the bias voltage (in V), and the vertical axis represents the responsivity (in A / W). Responsivity is the ratio of photocurrent to the incident light power. Responsivity is a physical quantity that measures the ability of the detector to convert light; the higher the responsivity, the stronger the detector's ability to convert light.

[0071] Figure 6 This is a DC characteristic curve of the dark current of the germanium photodetector 100 in Example 1 when the bias voltage is -1V, -2V and -3V, as a function of the hot-tuning voltage. Figure 6 The horizontal axis represents the thermal voltage (in V), and the vertical axis represents the dark current (in A).

[0072] Figure 7 This is a DC characteristic curve of the photocurrent of the germanium photodetector 100 in Example 1 when the bias voltage is -1V, -2V and -3V. Figure 7 The horizontal axis represents the thermally adjustable voltage (in V), and the vertical axis represents the photocurrent (in A).

[0073] Figure 8 This is a DC characteristic curve of the responsivity of the germanium photodetector 100 in Example 1 when the bias voltage is -1V, -2V and -3V, as a function of the thermally modulated voltage. Figure 8 The horizontal axis represents the heat-adjustable voltage (in V), and the vertical axis represents the responsivity (in A / W).

[0074] Test results show that as the temperature of germanium absorption layer 13 increases (i.e., the thermal adjustment voltage increases), the dark current and responsivity increase simultaneously. When the thermal adjustment voltage is greater than 3V, the responsivity gradually enters saturation. At this point, further increases in temperature will no longer significantly increase the responsivity, while the dark current will still increase significantly. Therefore, it is reasonable to select a thermal adjustment voltage of about 2.8V to 3.2V. Preferably, the thermal adjustment voltage is 3V.

[0075] Figure 9 The graphs show the DC characteristics of the photocurrent as a function of bias voltage for incident light at 1550 nm under heated and unheated conditions in Examples 1, 2, 3 and 4. Figure 10 The graphs show the DC characteristics of the photocurrent as a function of bias voltage for incident light at 1600 nm under heated and unheated conditions in Examples 1 and 2. Figure 11 The graphs show the DC characteristics of the photocurrent as a function of bias voltage for incident light at 1630 nm under heated and unheated conditions in Examples 1 and 2. Figure 9 , Figure 10 , Figure 11The horizontal axis represents the bias voltage (in V), and the vertical axis represents the photocurrent (in A). The heat-adjustable voltage used during heating is 3V.

[0076] Figure 12 The figures show the DC characteristics of the responsivity of 1550nm incident light under heated and unheated conditions in Examples 1, 2, 3 and 4 as a function of bias voltage. Figure 13 The graphs show the DC characteristics of the responsivity of 1600nm incident light under heated and unheated conditions in Examples 1 and 2, as a function of bias voltage. Figure 14 The graphs show the DC characteristics of the responsivity of 1630nm incident light under heated and unheated conditions in Examples 1 and 2, as a function of bias voltage. Figure 12 , Figure 13 and Figure 14 The horizontal axis represents the bias voltage (in V), and the vertical axis represents the responsiveness (in A / W). The thermal adjustment voltage used during heating is 3V.

[0077] First, for the three wavelengths of light mentioned above, increasing the temperature can increase the responsivity and photocurrent of the detector. However, as the size of the germanium absorption layer 13 increases, the effect of increasing the temperature on improving responsivity and photocurrent gradually decreases. For example, at a bias voltage of -3V and a wavelength of 1600nm, the responsivity of a 0.5μm×10μm detector without heat adjustment is 0.3A / W, while it increases to 0.7A / W after heat adjustment. However, the responsivity of a 0.5μm×40μm detector without heat adjustment is 0.66A / W, while it is only 0.68A / W after heat adjustment. In other words, at the same wavelength, bias voltage, and heat adjustment voltage, as the size of the germanium absorption layer 13 increases, the effect of heat adjustment on increasing responsivity and photocurrent weakens. This is because the photocurrent gradually reaches saturation.

[0078] Secondly, at -1V, for a detector with dimensions of 0.5μm*10μm, the photocurrent and responsivity gradually decrease with increasing wavelength, indicating that germanium has a low absorption rate for long-wavelength light. Regarding responsivity, at 1550nm, the responsivity without heating and with heating are 0.813 A / W and 0.842 A / W, respectively; at 1600nm, the responsivity without heating and with heating are 0.2 A / W and 0.67 A / W, respectively; and at 1630nm, the responsivity without heating and with heating are 0.12 A / W and 0.95 A / W, respectively. It can be seen that the enhancement effect of heating on the detector responsivity becomes more significant with increasing wavelength. Germanium can be detected in the 1550nm band under normal conditions, so heating does not significantly enhance the responsivity of the device. For the 1600nm and 1630nm bands, which are already in the L band, heating can significantly improve the light absorption rate of germanium, thereby increasing the photocurrent and responsivity of the device. This proves the effectiveness of heating in extending the wavelength detection range.

[0079] Figure 15 The frequency response curves of the germanium photodetector 100 of Example 1 under heated and unheated conditions with bias voltages of -2V and -4V, respectively. Figure 16 The frequency response curves of the germanium photodetector 100 in Example 2 under heated and unheated conditions with bias voltages of -2V and -4V, respectively.

[0080] Depend on Figure 15 and Figure 16 It can be seen that the detector bandwidth changes relatively little with the change in bias voltage. For a 10µm device, the -3dB bandwidth is 33.5GHz at a bias voltage of -2V and 34.5GHz at a bias voltage of -4V. For a 20µm device, the -3dB bandwidth is 31.5GHz at a bias voltage of -2V and 34GHz at a bias voltage of -4V. After introducing thermal tuning, the -3dB bandwidth of Examples 1 and 2 increases significantly. Example 1's -3dB bandwidth increases to 59GHz at a bias voltage of -2V and to 62.5GHz at a bias voltage of -4V, while Example 2's increases to 45GHz at a bias voltage of -2V and to 60GHz at a bias voltage of -4V. In other words, thermal tuning can effectively increase the detector bandwidth when the bias voltage increases.

[0081] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A germanium photodetector with tunable detection wavelength, characterized in that, include: A germanium detector layer includes a substrate layer, a PIN structure layer, and a germanium absorption layer stacked sequentially, wherein the germanium absorption layer is located above the intrinsic region of the PIN structure layer; An isolation layer is formed above the germanium detector layer. The isolation layer has a groove and two first electrode vias. The groove is located above the germanium absorption layer and is spaced apart from the germanium absorption layer. The groove includes a resistor cavity and two mutually isolated second electrode vias whose bottoms are connected to the resistor cavity. Two working electrode layers are respectively formed in the two first electrode through holes; A thermally adjustable resistor layer is disposed within the resistor cavity; Two thermally adjustable electrode layers are respectively formed in the two second electrode vias; A thermally adjustable circuit, connected to the two thermally adjustable electrode layers, is used to provide a thermally adjustable voltage to the thermally adjustable resistor layer.

2. The germanium photodetector with tunable detection wavelength according to claim 1, characterized in that, The two working electrode layers are formed by two depositions, and the thermally adjustable resistor layer and the two thermally adjustable electrode layers are formed simultaneously during the second deposition of the two working electrode layers.

3. The germanium photodetector with tunable detection wavelength according to claim 1, characterized in that, A heat-conducting layer is formed on the bottom wall of the resistive cavity.

4. The germanium photodetector with tunable detection wavelength according to claim 3, characterized in that, The resistor cavity has two opposite sidewalls, which are arranged at intervals with the two working electrode layers, and a heat insulation layer is formed at the two sidewalls.

5. The germanium photodetector with tunable detection wavelength according to claim 1, characterized in that, The orthogonal projection of the germanium absorption region onto the thermally adjustable resistive layer lies within the thermally adjustable resistive layer.

6. The germanium photodetector with tunable detection wavelength according to claim 5, characterized in that, The orthogonal projection of the germanium absorption region onto the intrinsic region lies within the intrinsic region.

7. The germanium photodetector with tunable detection wavelength according to any one of claims 1-6, characterized in that, The material of the thermally adjustable resistive layer is titanium nitride, tantalum nitride, chromium nitride, titanium carbide, silicon carbide, or aluminum oxide.

8. The germanium photodetector with tunable detection wavelength according to claim 7, characterized in that, The thickness of the germanium absorber layer is any value between 300nm and 400nm, the thickness of the thermally adjustable resistor layer is any value between 100nm and 150nm, the distance between the thermally adjustable resistor layer and the germanium absorber layer is any value between 2μm and 2.3μm, and the sheet resistance of the thermally adjustable resistor layer is 10Ω / □ -15Ω / □ Any value in the range.

9. The germanium photodetector with tunable detection wavelength according to claim 8, characterized in that, The thermal adjustment voltage is any value between 2V and 4.5V.

10. The germanium photodetector with tunable detection wavelength according to claim 9, characterized in that, The thermal adjustment voltage is any value between 2.8V and 3.2V.

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