Observation of indium-vacancy and indium-hydrogen interactions in Hg1−xCdxTe

Abstract

We have used a nuclear hyperfine technique, perturbed γγ angular correlation (PAC), to study the interactions between111In and native defects and impurities in Hg1−xCdxTe. The PAC technique uses the quadrupole interaction of111In with local electric field gradients to characterize the local environment of this donor dopant. We observed that when In was diffused into a bulk or thin film sample of Hg1−xCdxTe (x=0.21 and x=0.3) at 350°C and the sample was slow cooled, the In occupied sites with near-cubic symmetry, presumably the substitutional metal site. However, when the sample was quenched, a fraction of the In was incorporated into defects characterized by quadrupole interaction strengthsvQ1 andvQ2 and asymmetries of ν1=ν2=0.08. These defects are attributed to the trapping of a metal vacancy at a next-nearest neighbor site to the In atom. The introduction of hydrogen by boiling the samples in distilled water for >4h eliminated the previously observed PAC signals and created defects characterized byvQ3=35 MHz, ν3 <0.1 andvQ4=MHz, ν4 <0.1. These defects are attributed to the decoration of the In-VHg complex by a hydrogen atom. Hall effect measurements showed that hydrogenation increased the hole concentration in p-type quenched samples and even converted n-type indium-doped samples to p-type. A possible model for hydrogen incorporation which includes self-compensation by vacancy creation is suggested.