Lateral photovoltaic mid-infrared detector with a two-dimensional electron gas at the heterojunction interface

Mid-infrared (MIR) detection systems are pursuing element detectors with a high operating temperature, fast response speed, and high sensitivity to satisfy the increasing performance requirements that conventional detectors are unlikely to achieve. In this paper, we report a lateral photovoltaic MIR detector (LPVMIRD) based on a two-dimensional electron gas (2DEG) at the polar zincblende/rocksalt interface of CdTe/PbTe (111) heterojunctions (HJs). The LPVMIRDs possess identical asymmetric structures and operate without external biased voltage. Following the working principle of the LPVMIRDs, an analytical model is established where device performances are predicted theoretically. The proposed model is also applicable to other HJ systems based on a 2DEG. Furthermore, the LPVMIRDs are developed experimentally, and through infrared photoresponse characterizations, their response is revealed to originate from the intrinsic transition of PbTe caused by the unique energy-band alignment of the HJs. At a wavelength of 3 µm, the highest detectivity of the fabricated LPVMIRDs reaches 1.5×1010 Jones. Moreover, the infrared impulse responses demonstrate an extremely fast response speed. The impressive performance characteristics of the LPVMIRDs are promising for applications in uncooled MIR detection.