Sensitive photodetectors that operate at a wavelength of 2 μm are required for applications in sensing and imaging but state-of-the-art devices are severely limited by high dark current density (J_dark). The narrow-bandgap materials required for mid-infrared (2–5 µm) detection are plagued by carrier recombination and band-to-band tunnelling; as a result, detectors must be operated at cryogenic temperatures. HgCdTe is currently the most commonly used materials system for these applications and has achieved J_dark = 3 × 10⁻⁴ A cm^–2 at a gain of 10 while operating at 125 K. Here, we report the details and results for avalanche photodiodes for 2-μm detection based on a separate absorption, charge, and multiplication design in the Al_xIn_1–xAs_ySb_1–y materials system. We achieve comparable J_dark between 200–220 K and demonstrate very low excess noise (k ≈ 0.01) and gain >100 at room temperature. Such avalanche photodiodes could prove useful for receivers for eye-safe light imaging, detection and ranging.

传感和成像应用需要在2μm波长下工作的灵敏光电检测器，但是最新的设备受到高暗电流密度（J _dark）的严重限制。中红外（2–5 µm）检测所需的窄带隙材料受到载流子重组和带间隧穿的困扰。结果，检测器必须在低温下运行。HgCdTe是目前这些应用中最常用的材料系统，其J _dark  = 3×10 ^-4  A cm ^{– 2}在125 K下工作时增益为10。在这里，我们报告基于Al _x In _{1– x} As _y Sb _1中单独的吸收，电荷和倍增设计的用于2μm检测的雪崩光电二极管的详细信息和结果_{- ý}材料系统。我们获得相当Ĵ_暗200-220 K的和表现出非常低的过量噪声（ķ  ≈0.01），并在室温增益> 100。这种雪崩光电二极管可能被证明对接收器有用，可用于人眼安全的光成像，检测和测距。