Properties of Al Schottky Contacts on CdTe(111)Cd Surface Treated by He and H₂ Plasmas

Abstract

We investigated the effect of plasma treatments using He and H 2 gases on the electrical properties of Schottky CdTe diodes. The composition of the initial CdTe surface was Te-rich owing to Br-methanol etching. However, after the plasma treatments, the Te-rich layer was removed from the CdTe surface and the surface composition became stoichiometric. The plasma treatment improved the rectification properties of the Al Schottky CdTe diode. Furthermore, by adopting a guard-ring electrode, the reverse current of the CdTe diode decreased by more than one order compared with that of the CdTe diode without a guard-ring electrode. We evaluated the barrier height and ideality factor from current-voltage characteristics. The barrier heights of the CdTe diodes after He and H 2 plasma treatments were 0.75 and 0.73 eV, respectively.

Characterization of Functional Layers of CdTe Crystals Subjected to Different Surface Treatments

“…The samples were polished by mechanical and chemical procedures. The crystallographic feature of CdTe(111) samples is the presence of two polar surfaces namely Cd-terminated and Te-terminated ones and results of surface processing of the different stoichiometric surfaces can differ [7]- [9] and [14]. The measurements were performed on the Te-terminated face ( mm ) of CdTe crystals.…”

“…The performance of high energy radiation detectors depends on the quality of detector-grade CdTe single crystals with desired characteristics and on electrical contact design. The properties of the metal-CdTe interface are strongly affected by treatments of the crystal surface before electrical contact deposition therefore, surface processing plays a major role in development and fabrication of CdTe-based X-and -ray detectors [4]- [7].…”

“…Ohmic type detectors require obtaining a chemically clean and structurally perfect CdTe surface. For fabrication of diode type detectors, the different surface treatments are applied to modify the surface states of CdTe crystals, provide corresponding bending the energy bands and, thus, to form a high Schottky barrier or electrical junction [3]- [7].…”

Surface-Barrier Solar Cells Based On Monocrystalline Cadmium Telluride with the Modified Boundary

“…Finally, SBDs can have much lower values of series resistance R 0 comparing with the p-n junctions and heterojunctions, as they have one semiconductor region in place of two. However, many of the recent papers (Amanullah, 2003;Mason et al, 2004;Kim et al, 2009Kim et al, , 2009Gnatyuk et al, 2005;Higa et al, 2007) are rather dedicated to ionizing radiation detectors based on high-resistive CdTe. In contrast with SC, here the surface effects are of far lower importance because ionizing particles penetrate deeper into the material.…”