High Temperature Tolerant Mid-Wavelength Infrared Avalanche Photodiodes with Separated Fully-depleted Absorption, Multiplication Region

Mid-wavelength infrared (MWIR) avalanche photodiodes (APD) are extensively employed in rapid, high-precision detection as well as thermal imaging in complex context due to their superior sensitivity, fast response, and high gain. However, conventional MWIR APD’s detection typically requires lowtemperature operation to relieve signal-to-noise limitations imposed by high dark currents in narrow bandgap materials. To address this challenge, we present the high-temperature-operating MWIR avalanche photodiode with a separated fullydepleted absorption, multiplication region (SFDAM) structure to suppress the diffusion dark current and minimize the excess noise. The proposed APD can cope with infrared light well up to 4.2 µm, and exhibits low dark current density at unit gain that nearly an order of magnitude lower than the theoretical diffusion current limitation at elevated temperatures of 160 K. At 80 K, the device achieves comparable gain-normalized dark current density (GNDCD) still <6×10-10A/cm 2 at gain < 20 and demonstrates low excess noise < 1.67. At a high temperature of 160 K, the GNDCD preserves consistently below 2×10−6 A/cm 2 for gain values less than 189, while the excess noise holds below 1.4 and the noise equivalent power is <7.2×10 −16 W/ Hz of 3.5 µm. The device is also validated for imaging weak targets up to 200 km away. These results enable the SFDAM APDs are promising and desirable for future high-temperature-operating MWIR detection and likely the photon-starved applications.