engleski

The role of cation vacancy in compensation of II-VI compounds by fast diffusors - example of Cu in CdS

Defects responsible for compensation of CdS doped with fast diffusors were studied, using perturbed angular correlation spectroscopy (PAC). Cu was evaporated on CdS containing 111In probe atoms, and annealed at room temperature (RT). This resulted in gradual increase of pairing between substitutional 111In atoms and native cadmium vacancies, VCd, up to 100% in cca 7 days period. The model is presented which explains these results as well as electrical compensation of CdS by Cu: The RT in-diffusion of Cu donors into CdS provokes simultaneous in-diffusion of cadmium vacancies, which are double acceptors. Hence Cu compensates CdS crystal indirectly, by bringing into the crystal new VCd, that pair with existing donors causing their electrical compensation. Model explains consistently experimental results on Cu doped CdS and also reconciles two widely accepted but apparently contradictory assumptions: one, that Cu in CdS is a fast diffusor which moves as an interstitial, and hence is a donor, and the other, that Cu compensates donors in CdS and hence effectively acts as an acceptor (31 References).

annealing; cadmium compounds; compensation; copper; diffusion; II-VI semiconductors; impurity states; indium; perturbed angular correlation; vacancies (crystal).

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