The first demonstrated achievement of p on n-type activated junctions in HgCdTe material by arsenic ion implantation is reported. The junctions were formed by treating the implant as a finite diffusion source in the post-implant anneals. The materials employed for this study were n-type indium impurity-doped liquid phase epitaxy HgCdTe grown on CdTe. Arsenic was selected as the candidate acceptor impurity since it activated during post-implanted anneals in Hg vapor. The arsenic concentration profile determined by secondary ion mass spectroscopy showed that during post-implant anneal a complex diffusion mechanism redistributes the arsenic. The activation efficiency appears to be mechanism dependent. In the junction region the implant activation efficiency is about 50%. Junction depth can be controlled by varying arsenic diffusion and background carrier concentration. Junction depths determined by the electron beam induced current technique were consistent with the differential Hall electrical profiles. A p on n junction is shown with excellent rectification characteristics and high breakdown voltage (sharp at 2.5 V and 77 °C). This was obtained from a liquid phase epitaxy Hg1−xCdxTe, with a compositional factor of x=0.23.
This work reports on two significantly different methods to form junctions in Hg1−xCdxTe by ion implantation: a ‘‘displaced Hg diffusion source’’ for n-on-p junctions and an ‘‘implanted species diffusion source’’ for p-on-n devices. For each one, the role of background impurities, stoichiometric defects, and implanted species of junction formation have been determined. In spite of superficial damage created by the implant, these methods produced implanted junctions of either type with low damage in the near-junction region, resulting in excellent electrical characteristics.
A combination of organometallic and isothermal vapor phase epitaxy was used sequentially to grow CdTe and Hg1−xCdxTe on GaAs substrates. Photodiodes in the Hg1−xCdxTe show properties comparable to the best Hg1−xCdxTe grown by liquid phase epitaxy. Resistance-area products were ≥107 Ω cm2 and >104 Ω cm2 at 77 K for Hg1−xCdxTe with cut-off wavelength of 3.73 and 5.54 μm at 77 K, respectively. The backside-illuminated spectral response was broadband with peak external quantum efficiencies typically >50% (without antireflection coating).
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.