Hydrogenation of ZnS passivation on narrow-band gap HgCdTe

Due to the narrow band gap of HgCdTe required for infrared photodetectors, the device performance is readily influenced by surface effects. This lette r examines the effect that hydrogenation has on the quality of industry-sta ndard ZnS passivating films. The hydrogenation is achieved by exposing the samples to a H-2/CH4 plasma that is present during a reactive ion etching p rocess. The results show a marked improvement of the passivant/substrate in terface for hydrogenated devices with a reduction of the average fixed inte rface charge density to 3.5x10(10) cm(-2), accompanied by a sixfold decreas e in the standard deviation. The advantage of this method of hydrogenation is that it is integrated into the reactive ion etch processing for mesa for mation or p-type to n-type conversion in photoconductive or photovoltaic de vice fabrication, respectively. With the improvement of the ZnS passivation with hydrogenation, this method may alleviate the need for complex epitaxi al passivation processing. (C) 2000 American Institute of Physics. [S0003-6 951(00)03717-7].