Properties of Hg implanted Hg1? x Cd x Te infrared detectors

Experimental performance parameters of Hg implanted Hg_1−x Cd _x Te photovoltaic detectors are analyzed. At 77K, for 8–14 μm band, a comparison is made between performances and theoretical ultimate diffusion limits in low frequency direct detection. Experimental features are well-explained by a model based on the Auger band-to-band process for carrier recombination. Peak detectivities exceeding 10¹¹ cm Hz^1/2W⁻¹, external quantum efficiencies as high as 90%, and zero-bias resistance-area products better than 1 Ω·cm² have been achieved in devices with 12 μm cutoff wavelengths. In the 3–5 μm band performances are far from the diffusion limit. Notwithstanding, at 77K zero-bias resistance-area products are better than 10⁴Ω·cm² and detectivities of the order of 10¹² cm Hz^1/2W⁻¹ were observed at 5 μm. Predominant generation-recombination contribution are present at room temperature in 1–1.3 μm photodiodes whose detectivities, primarily limited by the Johnson noise, at 1.3 μm are higher than 10¹¹ cm Hz^1/2W⁻¹ at 300 K. The high frequency response of the photodiodes is also discussed. Response times as low as 0.5 ns are reached despite some limitations arising from the implanted layer sheet resistance. Work supported by CNR-CISE contract No. 73.01435.