An improvement on short-wavelength photoresponse for a heterostructure HgCdTe two-color infrared detector

Abstract

Integrated HgCdTe two-color infrared detector arrays were fabricated and their spectral photoresponses measured. The top mid-wavelength infrared planar photodiode was processed by selective B+ implantation and the bottom short-wavelength infrared P–N homojunction photodiode formed in situ during MBE growth by indium impurity doping. A preliminary 256 × 1 linear focal plane array of SWIR/MWIR HgCdTe was fabricated by mesa isolation, passivation and metallization. Detailed investigations on the inner mechanism of the short-wavelength narrow effect commonly associated with integrated HgCdTe two-color detectors have been carried out by combining experimental work with analytical analysis and numerical simulation. It is shown in this work that the short-wavelength narrow effect can be successfully alleviated by replacing the homostructure short-wavelength P–N junction with a heterostructure short-wavelength P–N junction which significantly improves the performance of the detector.