Hg 1− xCd xTe: electrical and structural changes induced by rapid thermal annealing

Abstract

The combined electrical and structural characterization of encapsulated HgCdTe annealed in a rapid thermal processor under different temperatures and times is presented. Hall effect measurements are used for the determination of the changes in carrier concentration and mobility produced during the annealing, while structural changes due to the thermal treatment are deduced from channelled proton-induced X-ray emission measurements. The results indicate that both the carrier concentration and mobility change homogeneously throughout the crystal, reaching equilibrium values that are only a function of the annealing temperature. The evolution towards equilibrium of each parameter can be fitted to exponential laws, the time constants being a function of the annealing temperature. However, the time required to reach the equilibrium mobility is always longer (by about ×3.5) than that needed to saturate the carrier concentration, for the same temperature. The crystallinity of the samples also shows a dependence on the annealing temperature. These changes are explained on the basis of generation and annihilation of mercury vacancies through the interaction with tellurium precipitates.