PHOSPHORUS IMPURITIES IN MGXZN1-XTE ALLOYS

P-doped MgxZn1-xTe alloys (0 less than or equal to x less than or equa l to 0.28) are characterized using room-temperature electrical, optica l, and photoelectric measurements. The electrical properties (hole con centration and mobility) indicate an increasing compensation with the increase of Mg content. The donor impurities are attributed to P. The optical absorption spectrum exhibits a peak situated at 1.06 eV, indep endent of composition. Supportive evidence is obtained for the assignm ent of this peak to electronic transitions in the shallow P acceptor l evel originating from the spin-orbit band. The perturbations in the lo cal potential lead to a broadening of the absorption peak and to the a ppearance of density-of-states tails at the edges of the principal ban ds. The spectral response of indium surface barriers on undoped and P- doped crystals is investigated. It is found that P doping leads to a l owering of the barrier height and to a shift in the high-energy edge o f the spectral response toward lower energies. The latter is attribute d to the presence of a thin insulating interfacial layer and a high de nsity of interface states in the P-doped contacts. It is suggested tha t P has a role in determining the characteristics of the interface. (C ) 1995 American Vacuum Society.