Dark current and noise measurements in InAs/GaSb superlattice detectors

Abstract

Infrared detectors based on InAs/GaSb superlattices (SL) have recently emerged as a promising technology for high performance infrared (IR) imaging systems. In this paper, we present the results of dark current and noise measurements realized on MWIR superlattice single detectors. The SL structure was made of 8 InAs monolayers (MLs) and 8 GaSb MLs, for a total thickness of 2μm. This structure exhibits a cut-off wavelength of 4.8μm at 77K. An original chemical etching solution was designed to obtain smooth mesa sidewalls, followed by a simple passivation technique. Dark current measurements were carried out to prove the good quality of both the etching and the passivation steps. The measured R0A product reaches the state-of-the-art values at 80K. Noise measurements were also performed under dark conditions. The detectors under test proved to be Schottky-limited on a range of bias voltage of 200mV typically, which confirms the very good quality of the technological process.