Ultrahigh-Speed Mid-Infrared Photodetectors With 2-D Electron Gas in a CdTe/PbTe Heterojunction

Abstract

A CdTe/PbTe heterojunction (HJ) yields two-dimensional electron gas (2DEG) with a high electron density and mobility. Ultrahigh-speed and room-temperature operating mid-infrared photodetectors are developed with the 2DEG. The photoresponse of the detectors originates from the intrinsic response of PbTe by virtue of the conduction-band and valence-band alignment of the HJ. The extremely short rise and decay photoresponse time demonstrate a major advantage of the 2DEG. At $ \lambda = {3.0}\,\, \mu \text{m}$ and a bias voltage of 100 mV, the responsivity and detectivity reach 0.94 A/W and ${2} \times {10}^{{10}}$ Jones, respectively. The excellent performance of the detectors renders promising applications in novel mid-infrared frequency detection systems.