H2-based dry plasma etching for mesa structuring of HgCdTe
Authors: Smith, E.; Musca, C.; Redfern, D.; Dell, J.; Faraone, L.
Source: Journal of Electronic Materials, Volume 29, Number 6, June 2000 , pp. 853-858(6)
Abstract:An experimental study has been carried out on the performance of n-type x = 0.31 HgCdTe photoconductive detectors in order to evaluate two different etching techniques; dry plasma etching, in the form of H2/CH4 reactive ion etching (RIE), and wet chemical etching using bromine in hydrobromic acid. Two-dimensional laser beam-induced current (LBIC) imaging was employed as an in-line process monitoring tool to evaluate the lateral extent of reactive ion etching (RIE) induced doping changes in the HgCdTe epilayer following mesa delineation. Responsivity and noise measurements were performed on fabricated mid-wavelength infrared (MWIR) photoconductive devices to evaluate the influence dry plasma etching has on material properties. For a signal wavelength of 3 µm, 60° field of view, and a temperature of 80 K, background limited D λ * performance was recorded for wet chemical processed devices but not for the dry plasma processed devices. The D λ * values obtained for wet chemical and dry plasma etched photoconductive detectors were 2.5×1011 cmHz1/2W−1 and 1.0×1010 cmHz1/2W−1, respectively. Mercury annealing, which has been shown to restore the electrical properties of dry plasma processed HgCdTe, could be used to lessen the influence that RIE dry plasma etching has on photoconductor detector performance.
Document Type: Research article
Publication date: 2000-06-01