Design and performance of GaSb‐based quantum cascade detectors
Miriam Giparakis, Andreas Windischhofer, Stefania Isceri, W. Schrenk, Benedikt Schwarz, G. Strasser, A. M. Andrews
Abstract
Abstract InAs/AlSb quantum cascade detectors (QCDs) grown strain‐balanced on GaSb substrates are presented. This material system offers intrinsic performance‐improving properties, like a low effective electron mass of the well material of 0.026 m 0 , enhancing the optical transition strength, and a high conduction band offset of 2.28 eV, reducing the noise and allowing for high optical transition energies. InAs and AlSb strain balance each other on GaSb with an InAs:AlSb ratio of 0.96:1. To regain the freedom of a lattice‐matched material system regarding the optimization of a QCD design, submonolayer InSb layers are introduced. With strain engineering, four different active regions between 3.65 and 5.5 µm were designed with InAs:AlSb thickness ratios of up to 2.8:1, and subsequently grown and characterized. This includes an optimized QCD design at 4.3 µm, with a room‐temperature peak responsivity of 26.12 mA/W and a detectivity of 1.41 × 10 8 Jones. Additionally, all QCD designs exhibit higher‐energy interband signals in the mid‐ to near‐infrared, stemming from the InAs/AlSb type‐II alignment and the narrow InAs band gap.