Vapour‐Pressure Investigations of Impurity Diffusion and Solubility in AII–BVI Compounds Demonstrated for the System CdS:Au:S₂

It is shown that for investigations of disorder problems in A II –B VI compounds it is relevant to measure the diffusion coefficient D and the solubility S as functions of the vapour pressure p of the components. Using the tracer technique this method is exemplified in detail for a cation impurity diffusion process in the system CdS:Au:S 2 . The measured concentration profiles C ( x ) are not of Fick's type. After eliminating surface and dislocation diffusion (Fisher analysis), D ( T , p , C ) and also simultaneously S ( T , p ) can be obtained. The results are explained in a disorder model with controlled intrinsic disorder. It is found that gold diffuses in CdS via singly‐charged cadmium vacancies and acts as a singly‐charged acceptor.