Semiconductors with structurally determined vacancies - PAC studies

Ternary semiconductors of type square A(II)B(2)(III)C(4)(VI) with an ordere d array of vacancies were investigated by PAC. Thereby the six probes Cd-11 1m, Cd-117(In-117), In-111(Cd-111), Ag-111(Cd-111), Br-77(Se-77) and Kr-77( Br-77) were applied. The positions of the different probes are determined a nd the corresponding electric field gradients by the WIEN 95 code calculate d. By Ag-111(Cd-111)-probes the vacancies could be substituted. The electro nic charge density distributions are discussed. At elevated temperatures th e substances show order-disorder transitions. As compared to the X-ray diff raction patterns the beginning of disorder is observed by PAC at distinctly lower temperatures.