Semiconductor single-photon detector with wide spectrum and high detection efficiency

Abstract

The invention provides a wide-spectrum high-detection-efficiency semiconductor single-photon detector. The device is characterized in that the single-photon detector is composed of a light source (1), a spectroscope (2), a wide-spectrum single-photon avalanche photodiode (3), a first holophote (4), a second holophote (5) and a third holophote (6), wherein the wide-spectrum single-photon avalanche photodiode (3) is composed of a Si single-photon avalanche photodiode (31) and an InGaAs single-photon avalanche photodiode (32). The method can be used for measuring extremely weak light, and can be widely applied to the fields of laser ranging, quantum communication, quantum key distribution, medical imaging and the like.

Description

(I) Technical field

[0001] The invention relates to a semiconductor single-photon detector with a wide spectrum and high detection efficiency, belonging to the technical field of photoelectric detection. (II) Background technology

[0002] A single-photon detector (SPD) is a photoelectric device that can detect a single photon. It can convert a single photon signal into an electrical signal, thereby realizing the detection of extremely weak light signals. Because single-photon detectors have ultra-high sensitivity and can detect light signals with extremely low light intensities, they are widely used in quantum key distribution, lidar, space quantum communication, biomedical imaging and other fields. According to different technical solutions, single-photon detectors can be divided into photomultiplier tubes (PMT), single-photon detectors based on avalanche photodiodes (APD), single-photon detectors based on quantum wells (QW), superconducting nanowire single-photon detectors (SNSPD), etc. Single-Photon Avalanche Diode (SPAD) utilizes the internal photoelectric effect and avalanche breakdown effect of an avalanche photodiode working in Geiger mode to detect weak light signals. Compared with other single-photon detection devices, it has the advantages of small size, easy integration, and low power consumption. In addition, it has the performance advantages of being insensitive to electromagnetic noise, not requiring extreme low temperature conditions, and having higher time resolution.

[0003] Traditional photodetectors generally work within a single wavelength band, and photodetectors used in different wavelength bands are generally made of different photosensitive materials. For example, silicon materials are limited by their bandgap width, making silicon-based photodetectors suitable for detecting visible light, but unable to detect light waves with wavelengths above 1100nm, while InGaAs photodetectors are mainly used to detect near-infrared light. In some applications, environmental conditions may change, including changes in lighting conditions. Wide-spectrum detectors can adapt to different lighting conditions and provide stable performance and reliable data output. Therefore, it is of great significance to study wide-spectrum photodetectors. Therefore, it is particularly important to design a photodetector with a wide spectrum response and high detection efficiency.

[0004] The current technical solution is to adjust the response band by changing the junction depth. For example, the traditional silicon-based SPAD has a good quantum efficiency at 400-600nm. Researchers have designed a deeper junction depth to increase the response band to the near-infrared spectral region, or designed a double-junction SPAD to have two response peaks to expand the response spectrum. In order to expand the response spectrum of single-photon avalanche photodetection and reduce the dark count rate, researchers have designed different detector structures. For example, Cristiano et al. made a p-shaped detector with an octagonal shape. + / n well junction, at room temperature, the SPAD shows a maximum single-photon detection probability of 41% (Niclass, Cristiano, et al. "A 130-nm CMOS single-photon avalanche diode." Optoelectronic Devices: Physics, Fabrication, and Application IV. Vol. 6766. SPIE, 2007.); Gulinatti et al. designed an infrared enhanced SPAD, which has a 40% detection probability for light with a wavelength of 800nm ​​(Gulinatti, Angelo, et al. "New silicon SPAD technology for enhanced red-sensitivity, high-resolution timing and system integration." Journal of Modern Optics 59. 17 (2012): 1489-1499.); Shimada et al. proposed a high-performance 3D stacked back-illuminated single-photon avalanche diode pixel array sensor, which successfully obtained a detection efficiency of more than 20% at 940nm using a 3.0V over-bias (Shimada, Shohei, et al. al. "A back illuminated 6μm spad pixel array with high PDE and timing jitter performance." 2021IEEE International Electron Devices Meeting (IEDM). IEEE, 2021.). Although several SPAD devices with higher detection probabilities are proposed in the above literature, their peak responses are all single peaks.In 2013, Henderson et al. used 130nm low-voltage CMOS technology to make a dual-junction single-photon avalanche diode. The detection probability of this dual-junction SPAD at a wavelength of 450nm is 32%, and the detection probability at a wavelength of 670nm is 29% (Henderson, Robert K., Eric AG Webster, and Lindsay A. Grant. "A dual-junction single-photon avalanche diode in 130-nm CMOS technology." IEEE electron device letters 34.3 (2013): 429-431.); in 2021, Jin Xiangliang et al. proposed a dual-peak SPAD structure that responds in the visible light region and the infrared light region respectively. The photon detection probability of this SPAD reaches 32% at 520nm and 12% at 840nm (Zhang Weiyu, Wang Yang, Jin Xiangliang. Design and optimization of dual-peak response CMOS single-photon detector [J]. Acta Optica Sinica, 2021, Vol. 41: 26-31).

[0005] In summary, the shortcomings of these designs are as follows: 1. The existing single-peak SPAD can only detect light of a specific wavelength. For a fixed single absorption material, changes in the structure have very limited effects on the change in the peak wavelength of the spectral response; 2. There is a large difference in the detection efficiency of the two peaks of the existing dual-peak SPAD, and it is impossible to detect both bands with high efficiency; 3. It is impossible to output response currents of different bands at the same time, and can only respond to one specific wavelength at the same time, and the detection efficiency is low under complex lighting conditions.

[0006] In order to solve the above problems, the present invention discloses a semiconductor single-photon detector with wide spectrum and high detection efficiency, which can be widely used in laser ranging, quantum communication, quantum key distribution, and medical imaging. The present invention integrates Si single-photon avalanche photodiode with InGaAs single-photon avalanche photodiode, thereby realizing wide-band optical signal detection from visible light to short-wave infrared, and expanding the application range of the detector. Silicon-based SPAD has high detection efficiency, low dark count rate and high clock resolution in the visible light band (about 400-1000nm), which is very suitable for the detection of visible light and near-infrared light. InGaAs-based SPAD exhibits excellent detection performance in the short-wave infrared band (about 900-1700nm), which is suitable for long-distance communication, infrared imaging and quantum communication. By taking advantage of the advantages of different materials in their respective optimal working bands, the overall performance of the detector can be optimized, including improving detection efficiency, reducing noise and improving time resolution. This integration allows optical signals of different bands to be processed simultaneously in a single system, improving the flexibility and applicability of the system. (III) Summary of the invention

[0007] The purpose of the present invention is to provide a wide-spectrum high-detection-efficiency semiconductor single-photon detector, which comprises a light source (1), a spectroscope (2), a wide-spectrum single-photon avalanche photodiode (3), a first reflector (4), a second reflector (5), and a third reflector (6), wherein the wide-spectrum single-photon avalanche photodiode (3) comprises a Si single-photon avalanche photodiode (31) and an InGaAs single-photon avalanche photodiode (32).

[0008] The object of the present invention is achieved in that:

[0009] The optical signal generated by the light source (1) is incident on the spectroscope (2) and is divided into a visible light beam and an infrared light beam. The visible light beam is reflected by the first reflector (4) and vertically incident from the top to enter the wide-spectrum single-photon avalanche photodiode (3), and is detected by the Si single-photon avalanche photodiode (31). The infrared light beam is reflected by the second reflector (5) and the third reflector (6) and vertically incident from the bottom to the wide-spectrum single-photon avalanche photodiode (3), and is detected by the InGaAs single-photon avalanche photodiode (32). The top and bottom electrodes of the wide-spectrum single-photon avalanche photodiode (3) working under reverse bias respectively output response currents stimulated by the two light beams.

[0010] The light source (1) in the detector may be one of various light signals such as scattered or reflected light signals in biomedical imaging technology, light signals in optical communication systems, light pulse signals in laser radar systems, etc. The beam splitter in the detector may be a beam splitter of any shape such as a rectangle or a circle, or may be any optical experimental device that splits a beam of light into visible light and infrared light.

[0011] The wide spectrum single photon avalanche photodiode (3) of the detector is composed of two single photon avalanche photodiodes stacked up and down, with a Si single photon avalanche photodiode (31) on the top and an InGaAs single photon avalanche photodiode (32) on the bottom. The two are connected together through a common electrode Cathode in the middle, are located on the same central axis, and have a diameter of 20-300 μm.

[0012] The first total reflection mirror (4) in the detector is located directly above the wide-spectrum single-photon avalanche photodiode (3), the third total reflection mirror (6) is located directly below the wide-spectrum single-photon avalanche photodiode (3), and the second total reflection mirror (5) is horizontally aligned with the center of the third total reflection mirror (6).

[0013] Beneficial effects of the present invention:

[0014] In some applications, environmental conditions may change, including changes in lighting conditions. The wide-spectrum single-photon detector improved by the present invention can adapt to lighting conditions from visible light to near-infrared, and can receive light signals in a wider spectral range, thereby increasing the signal capture capability and providing stable performance and reliable data output. The wide-spectrum single-photon detector applied for by the present invention can detect light in two wavelength ranges at the same time, which helps to improve the resolution and accuracy of the data, and the information obtained is richer and more comprehensive. The wide-spectrum single-photon detector applied for by the present invention can cover multiple wavelength ranges, so it can be applied in a wider range. (IV) Description of the drawings

[0015] Figure 1 The invention discloses a schematic diagram of a semiconductor single-photon detector with a wide spectrum and high detection efficiency. The incident light generated by a light source (1) is divided into a visible light beam and an infrared light beam through a beam splitter (2). The visible light beam propagates in a horizontal direction, reaches a total reflection mirror (4), is reflected, enters a wide spectrum single-photon avalanche photodiode (3) from above, and is finally absorbed by a Si single-photon avalanche photodiode (31); the infrared light beam propagates in a vertical direction, reaches a total reflection mirror (5), is reflected by the total reflection mirror (5), reaches a total reflection mirror (6), is reflected, enters a wide spectrum single-photon avalanche photodiode (3) from below, and is finally absorbed by an InGaAs single-photon avalanche photodiode (32).

[0016] Figure 2 The schematic diagram of the structure of a wide-spectrum single-photon avalanche photodiode (3) in a detector. The wide-spectrum single-photon avalanche photodiode (3) of the detector is composed of two single-photon avalanche photodiodes stacked up and down, with a Si single-photon avalanche photodiode (31) on the top and an InGaAs single-photon avalanche photodiode (32) on the bottom. The two are connected together through a common electrode Cathode in the middle, are on the same central axis, and have a diameter of 20-300μm. The Si single-photon avalanche photodiode (31) is composed of a top electrode Anode1, a top SiO2 layer, a top epitaxial layer, a silicon-based substrate, and a common electrode Cathode from top to bottom. The top epitaxial layer is provided with a p+ region as an anode contact layer. The top Anode1 is connected to the anode contact layer and led out. Both sides of the anode contact layer are lightly doped to form a P-Well. The InGaAs single-photon avalanche photodiode (32) comprises a P-type anode electrode stacked in sequence. + -InP contact layer, n-InP multiplication layer, n + -InP charge layer, n-InGaAsP graded layer, n-InGaAs absorption layer and n + -InP contact layer, cathode Cathode and anode Anode2, P + -The outside of the InP contact layer is also provided with a P+ -Floating guard ring of InP.

[0017] Figure 3 The invention discloses a schematic structural diagram of a semiconductor single-photon detector with a wide spectrum and high detection efficiency, which comprises a light source (1), a spectroscope (2), a wide-spectrum single-photon avalanche photodiode (3), a first reflector (4), a second reflector (5), and a third reflector (6), wherein the wide-spectrum single-photon avalanche photodiode (3) comprises a Si single-photon avalanche photodiode (31) and an InGaAs single-photon avalanche photodiode (32). (V) Specific implementation methods

[0018] The present invention will be further described below in conjunction with specific embodiments.

[0019] Embodiment 1:

[0020] like Figure 1 As shown, a wide spectrum high detection efficiency semiconductor single photon detector comprises a light source (1), a spectroscope (2), a wide spectrum single photon avalanche photodiode (3), a first reflector (4), a second reflector (5), and a third reflector (6), wherein the wide spectrum single photon avalanche photodiode (3) comprises a Si single photon avalanche photodiode (31) and an InGaAs single photon avalanche photodiode (32). The Si single photon avalanche photodiode (31) comprises a top electrode Anode 1, a top SiO2 layer, and an n - Epitaxial layer, n + The contact layer and the cathode metal contact the cathode. - p + The region is used as the anode contact layer, the top Anode1 is connected to the anode contact layer and the two sides of the anode contact layer are lightly doped to form a P-Well, which serves as a guard ring to prevent premature breakdown of the edge. + Area and n - The epitaxial layer forms a PN junction, which causes the electric field to gather in this area and carriers to multiply here.

[0021] InGaAs single photon avalanche photodiode (32) is made of P + -InP contact layer, P-Well layer, n-InP multiplication layer, n + -InP charge layer, n-InGaAsP graded layer, n-InGaAs absorption layer and n + -InP contact layer, cathode Cathode and anode Anode2. The role of heavily doped InP contact is to form ohmic contact with metal, ensuring efficient current transmission and low energy loss. The n-InGaAs absorption layer collects photons to generate electron-hole pairs, and the multiplication region realizes carrier avalanche multiplication.+ The -InP charge layer is used to adjust the electric field size of the absorption layer and the multiplication layer. The role of the n-InGaAsP gradient layer is to act as a transition layer to reduce the barrier difference between the InP and InGaAs heterojunction interfaces, avoid carrier accumulation, and improve the response speed. The role of the P-Well as a floating guard ring is to reduce surface leakage current and prevent edge breakdown.

[0022] The optical signal generated by the light source is divided into two beams of visible light and infrared light by the beam splitter (2). The visible light beam is incident on the total reflection mirror (4) in the horizontal direction, and is reflected from the top to enter the Si single-photon avalanche photodiode (31). After the infrared light beam comes out of the beam splitter (2), it propagates in the vertical direction through the total reflection mirror (5) and the reflection mirror (6), and finally enters the InGaAs single-photon avalanche photodiode (32) from the bottom. When the detector is working, under the action of the reverse bias voltage, the photons in the visible light band are absorbed by the Si single-photon avalanche photodiode (31), and the photogenerated electron-hole pairs are separated and accelerated. When they have sufficient energy, they collide with lattice atoms to ionize and generate new electron-hole pairs. The new electron-hole pairs will continue to collide and ionize to generate more electron-hole pairs. The multiplied carriers are finally collected by the top electrode Anode1 to form a multiplied current. Photons in the near-infrared band will enter the interior of the InGaAs single-photon avalanche photodiode (32) and be absorbed in the InGaAs absorption layer, generating electron-hole pairs, i.e., photogenerated carriers. When the device is working under reverse bias, electrons generated in the absorption region drift to the n-type contact layer under the action of the electric field and finally enter the cathode, while holes drift toward the anode, pass through the gradient region and the charge region, and enter the InP multiplication region. When the electric field in the multiplication region causes the holes to obtain sufficient energy, an avalanche effect will occur. Under the action of the strong field, the holes collide with lattice atoms to ionize and generate new electron-hole pairs. The new electron-hole pairs will continue to collide and ionize to generate more electron-hole pairs. The carriers increase exponentially, and the multiplied carriers are finally collected by the top electrode Anode2 to form a multiplied current.

[0023] The embodiment of the present invention provides a wide spectrum high detection efficiency single photon detector, which can realize efficient single photon detection in a wide spectrum range. Compared with the prior art, the detector makes full use of the integrated structure design of Si single photon avalanche photodiode (31) and InGaAs single photon avalanche photodiode (32), realizes efficient detection of different spectra, has a compact structure, and meets the high detection efficiency requirements of single photon detectors in different spectrum ranges.

[0024] The above description is only a preferred embodiment of the present invention, and the protection scope of the present invention is not limited thereto. Any modifications and changes made by those skilled in the art within the spirit and scope of the present invention should be included in the protection scope of the claims of the present invention.

Claims

1. A semiconductor single-photon detector with wide spectrum and high detection efficiency. Its characteristics are: The single-photon detector is composed of a light source (1), a spectroscope (2), a wide-spectrum single-photon avalanche photodiode (3), a first total reflection mirror (4), a second total reflection mirror (5), and a third total reflection mirror (6), wherein the wide-spectrum single-photon avalanche photodiode (3) is composed of a Si single-photon avalanche photodiode (31) and an InGaAs single-photon avalanche photodiode (32); in the system, a signal generated by the light source (1) is transmitted to the spectroscope (2) and is divided into a visible light beam and an infrared light beam, and the visible light beam is reflected by the first reflection mirror (4). The reflection is vertically incident from the top of the detector to enter the wide-spectrum single-photon avalanche photodiode (3) and is detected by the Si single-photon avalanche photodiode (31). The infrared light beam is reflected by the second reflector (5) and the third reflector (6) and vertically incident from the bottom of the detector to the wide-spectrum single-photon avalanche photodiode (3) and is detected by the InGaAs single-photon avalanche photodiode (32). The top and bottom electrodes of the wide-spectrum single-photon avalanche photodiode (3) operating under reverse bias respectively output response currents stimulated by the two light beams.

2. The semiconductor single-photon detector with wide spectrum and high detection efficiency according to claim 1, characterized in that: The wide spectrum single photon avalanche photodiode (3) of the detector is composed of two single photon avalanche photodiodes stacked up and down, with a Si single photon avalanche photodiode (31) on the top and an InGaAs single photon avalanche photodiode (32) on the bottom. The two are connected together through a common electrode in the middle, are located on the same central axis, and have a diameter of 20-300 μm.

3. The semiconductor single-photon detector with wide spectrum and high detection efficiency according to claim 1, characterized in that: The light source (1) in the detector may be one of various light signals such as scattered or reflected light signals in biomedical imaging technology, light signals in optical communication systems, light pulse signals in laser radar systems, etc.

4. The semiconductor single-photon detector with wide spectrum and high detection efficiency according to claim 1, characterized in that: The beam splitter (2) in the detector may be a beam splitter of any shape such as a rectangle or a circle, or may be any optical device that splits a beam of light into visible light and infrared light.

5. The semiconductor single-photon detector with wide spectrum and high detection efficiency according to claim 1, characterized in that: The first total reflection mirror (4) is located directly above the wide-spectrum single-photon avalanche photodiode (3), the third total reflection mirror (6) is located directly below the wide-spectrum single-photon avalanche photodiode (3), and the second total reflection mirror (5) is horizontally aligned with the center of the third total reflection mirror (6).

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