Auto-Calibrated Charge-Sensitive Infrared Phototransistor at 9.3 µm.
Auto-Calibrated Charge-Sensitive Infrared Phototransistor at 9.3 µm.
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DOI：
10.3390/s23073635
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发表时间：
2023-03-31
期刊：
影响因子：
--
通讯作者：
Todorov Y
中科院分区：
文献类型：
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作者：
Bahrehmand M;Gacemi D;Vasanelli A;Li L;Davies AG;Linfield E;Sirtori C;Todorov Y
电荷敏感红外光电晶体管(CSIP)是一种中红外辐射的量子探测器，据报道，这种探测器具有出色的品质因数和灵敏度，可以进行单光子探测。CSIP的典型吸收区域由AlxGa1-xAs量子异质结组成，其中发生吸收的GaAs量子阱后面是一个三角形势垒，该势垒具有梯度x(Al)成分，将量子阱连接到源漏沟道。在这里，我们报告了一种设计用于9.3微米波长的CSIP，其中Al组分保持不变，而三角形势垒被隧道耦合量子阱所取代。因此，这种设计在概念上更接近于量子级联探测器(QCD)，后者是一种在中红外范围内进行探测的成熟技术。虽然以前报道的结构使用金属栅来耦合吸收量子阱中的红外辐射，但在这里，我们使用了45°楔形小平面耦合几何结构，允许简化和可靠地估计器件中的入射光子通量Φ。值得注意的是，这些探测器具有“自动校准”特性，仅通过测量电学特性和设备几何知识即可精确评估光子通量Φ。我们确定了CSIP探测器可以直接与其他单极量子探测器如量子井红外探测器(QWIP)和QCDs相比较的工作模式，并估算了相应的低温条件下的探测器优劣系数。测得其最大响应度R=720A/W，光导增益G~2.7×104，比QCDs和量子阱红外探测器(QWIP)的最大响应度大一个数量级。我们还评论了纳米天线概念在提高光子计数系统中CSIP效率方面的好处。
Charge-sensitive infrared photo-transistors (CSIP) are quantum detectors of mid-infrared radiation which have been reported to have outstanding figures of merit and sensitivities that allow single photon detection. The typical absorbing region of a CSIP consists of an AlxGa1-xAs quantum heterostructure, where a GaAs quantum well, where the absorption takes place, is followed by a triangular barrier with a graded x(Al) composition that connects the quantum well to a source-drain channel. Here, we report a CSIP designed to work for a 9.3 µm wavelength where the Al composition is kept constant and the triangular barrier is replaced by tunnel-coupled quantum wells. This design is thus conceptually closer to quantum cascade detectors (QCDs) which are an established technology for detection in the mid-infrared range. While previously reported structures use metal gratings in order to couple infrared radiation in the absorbing quantum well, here, we employ a 45° wedge facet coupling geometry that allows a simplified and reliable estimation of the incident photon flux Φ in the device. Remarkably, these detectors have an “auto-calibrated” nature, which enables the precise assessment of the photon flux Φ solely by measuring the electrical characteristics and from knowledge of the device geometry. We identify an operation regime where CSIP detectors can be directly compared to other unipolar quantum detectors such as quantum well infrared photodetectors (QWIPs) and QCDs and we estimate the corresponding detector figure of merit under cryogenic conditions. The maximum responsivity R = 720 A/W and a photoconductive gain G~2.7 × 104 were measured, and were an order of magnitude larger than those for QCDs and quantum well infrared photodetectors (QWIPs). We also comment on the benefit of nano-antenna concepts to increase the efficiency of CSIP in the photon-counting regime.