Conductivity type conversion in p- CdXHg1-XTe

Abstract

Investigations and comparative analysis of p-to-n type conductivity conversion processes on the identical samples of vacancy doped p-CdxHg–xTe (x 0.2) under ion-beam milling (IBM) and anodic oxide annealing and on the identical samples of As-doped p-CdxHg1–xTe (x 0.22) under IBM and anodic oxide annealing have been carried out. The conductivity type conversion has been observed at the considerable depth of the vacancy doped material both under IBM or under anodic oxide annealing while in the case with As-doped material only under IBM. It was considered that conversion in all these processes was determined by the mercury interstitial diffusion from corresponding mercury diffusion source and recombination with its native acceptors – cationic vacancies (in the first case) or with donor complex formations (in the second one). It has been shown that in the vacancy-doped p-CdxHg1–xTe the effective diffusion coefficients for the mercury interstitials that determines the depth of the converted layer are equal each other at equal temperatures either under thermal annealing in the saturated mercury vapour or anodic oxide annealing. It proves the identity of the mercury concentration in the diffusion source. Absence of the conversion under anodic oxide annealing in the As-doped p-CdxHg1–xTe is explained by insufficient Hg concentration in the source and it matches well with necessary condition for donor complex formation as it takes place under IBM.