Structure and electronic properties of the novel semiconductor alloy Cd1-xCuxTe

In this work an investigation of the structural and electronic properties o f the novel semiconductor alloy Cd1-xCuxTe is presented. The samples were p repared as thin films by rf sputtering on substrates made of Coming glass. X-ray diffraction patterns showed that the incorporation of Cu into CdTe di d not significantly affect the lattice parameters and that the incorporatio n of copper favors the growth of films preferentially oriented parallel to the (111) planes of cubic CdTe. Due: to its sensitivity to local atomic ord er, the samples were studied by micro-Raman spectroscopy. The transverse an d longitudinal optic modes regularly observed in CdTe were also found in th e Cd1-xCuxTe samples with frequencies variations of less than 2 cm(-1). The appearance of second and third harmonics of the longitudinal optic mode is indicative of high crystalline quality. The Raman bands become broader as a consequence of the disorder induced by the random incorporation of copper . From the Raman experiments it was also determined that the incorporation of Cu precluded the formation of Te clusters, which are commonly detected i n CdTe thin films and bulk samples. The band gap of the alloys measured by optical transmission and photoreflectance spectroscopies. tends to decrease with increasing copper content. The smallest band gap values were lower by approximately; 60 meV compared to those of pure CdTe. (C) 1999 American Va cuum Society. [S0734-2101(99)15904-9].