Multiple long wavelength infrared MOCVD grown HgCdTe photodetectors for high temperature conditions

This paper presents large area multiple photodetectors of the MOCVD grown HgCdTe heterostructures for operation at temperatures of (200-300)K in the long wavelength infrared range. Conventional long wavelength photovoltaic detectors operating at higher temperatures suffer from low dynamic resistance and multiple photodetectors idea solves this problem. Particular experimental steps are demonstrated starting from MOCVD technology, through etching, angled ion milling, angled contact metal deposition, assembly and electro-optical measurements. MOCVD technique with wide range of composition and donor/acceptor doping and without post growth annealing provides HgCdTe heterostructures for uncooled multiple detectors. CdTe buffer layer deposition allows HgCdTe heterostructure growth on GaAs substrates. Angled ion Ar+ milling optimal selection parameters is crucial for proper junction formation and conductivity type conversion. Theoretical modelling using APSYS platform supports designing of the detector’s structures. Presented technology enable to fabricate large area ( $4\times 4$ mm2) multiple photodetectors with detectivity $\text{D}^\ast $ exceeding 107 cmHz $^{1/2}\text{W}^{-1}$ at $10.6~\mu \text{m}$ and room temperature operation useful for many applications.