Development and application of quasi-planar InGaAsSb p-B-n devices for spectroscopic sensing

Abstract

Absorption fingerprints of substances such as glucose, acetone and CO2 fall within the short-wave infrared range (SWIR), in the wavelength range 1.7 μm -2.4 μm; improved detection of these substances will be impactful to health, wellbeing and the environment. A design of detector based on the emerging material system InGaAsSb with cut-off wavelengths in this range, 2.25 μm, is presented. By controlling the composition of the InGaAsSb, the cut-off wavelength can be extended beyond GaSb (1.7 μm) to a particular target with minimal leakage increase. Unbiased operation has been obtained using a p-B-n structure design and a quasi-planar device design with good optical power resolution (40 pW). At the current state of optimisation, D* is 9.4×10 10 Jones at 0 V bias and 2.0 μm which is approaching the much more mature extended InGaAs technology, grown mismatched on InP, with the same cut-off wavelength. InGaAsSb is grown on GaSb substrates which are increasingly popular for IR optoelectronics and being lattice matched will offer a higher yield in production compared to mismatched growth. With InGaAsSb, the GaSb-matched material system can support lattice matched epilayers exhibiting cut-off wavelengths from the near to the longwave infrared. This work looks towards future applications through evaluations and measurements of low concentration glucose solutions. These detectors show great promise for future commercial applications.