Influence of As flux on the micro-structures and dark current of InAs/InAsSb superlattice-based infrared detectors

Abstract

In this work, we present a study on the influence of As/In flux ratio during the molecular beam epitaxy growth on the material quality and thus dark current density of the InAs/InAsSb superlattice-based mid-wave infrared detectors. It was observed that a proper As/In flux ratio is essential to achieving higher material quality and thus lower dark current density for InAs/InAsSb superlattice-based detectors. It is also found that a smaller pixel size, a lower reverse bias and a lower operating temperature are essential for achieving a lower dark current density. The dark current of the InAs/InAsSb superlattice detectors grown with an optimized As/In ratio (e.g. 10 in this work) is dominated by diffusion current for the temperature range of 150–270 K, and tunneling current for the temperature range of 90–150 K. The absence of defect-related Shockley-Read-Hall dark current mechanism results in the ultra-low dark current density (2.53 × 10⁻⁶ A/cm²) and excellent device performance observed at 150 K in terms of a responsivity of 1.71 A/W, and a detectivity of 8.22 × 10¹¹ cm·Hz^1/2/W. Such excellent detector performance at 150 K suggests their great potential for high performance sensing and imaging applications at 150 K.