Design and optimization of mid-wavelength avalanche photodiodes based on III-V antimonides

To address the demand for high-gain, low-dark-current Avalanche Photodiodes (APD) in Mid-wavelength infrared (MWIR) detection, an APD utilizing InAs/GaSb type-II superlattices (T2SLs) was designed to enhance performance. A detailed study was performed to examine how the thickness and doping levels of the absorption and multiplication layers influence the internal electric field profile. The results indicate that the optimized structure achieves a uniform electric field distribution, with a peak electric field in the multiplication layer reaching 6.4×10⁵ V/cm. Under a bias voltage of 32 V, the device exhibits a gain of 52, and at the breakdown voltage of 62 V, the gain reaches 85.2. A peak responsivity of 3 A/W is achieved at a wavelength of 3.08 μm, effectively covering the 3–5 μm range. This work offers a theoretical reference for designing MWIR APD.