Effect of “M” and “B” superlattice barrier layers on dark current of long-wavelength infrared detectors

Abstract

This paper studies superlattice materials with M barrier (InAs/GaSb/AlSb/GaSb superlattice) and B barrier (InAs/AlSb superlattice) structures. Firstly, it introduces the diffusion current, generation-recombination current, tunneling current and surface leakage current in devices, and analyzes the factors affecting different dark current mechanisms. Secondly, it theoretically analyzes the influence of the two barrier structures on device performance. Finally, devices were fabricated using these two structures, and the device performance was characterized. At a bias voltage of −50 mV and operating temperature of 77K. The PπMN type long-wave infrared (LWIR) detector has an RA of 91.4 Ω cm2 and a LW dark current density of 3.51 × 10−4 A cm−2. The PπBN type LWIR detector has an RA of 439 Ω cm2 and a LW dark current density of 2.81 × 10−4 A cm−2. Meanwhile, by fitting the data at different temperatures, the activation energy Ea of the PπMN type LWIR detector is 119.8 meV, with dark current mainly determined by diffusion current and generation-recombination current. The activation energy Ea of the PπBN type LWIR detector is 126.2 meV, with dark current mainly determined by diffusion current. This experimentally verifies the dominant dark current mechanisms for the two barrier structures of LWIR detectors, providing strong support for the design of superlattice detector structures.