Influence of growth temperature on morphology and optical studies of InP/CdS heterostructures

Cadmium sulphide epitaxial layers have been grown on (111) 'P face' of indium phosphide substrates by chemical vapour deposition technique in which hydrogen is used as carrier gas. Deposition temperature is varied from 450 degrees C to 650 degrees C. Characteristic growth patterns have been observed on the as-grown surface of CdS. The crystal structures of the films deposited are found to depend upon the deposition temperature. At the optimum substrate temperature (610 degrees C) the hexagonal flat top morphology which is the two-dimensional nucleation of the wurtzite structure of CdS has been observed and at lower substrate temperatures star like growth hillocks and cubic form of CdS have been observed. Raman spectroscopy showed a dominant peak at about 303 cm(-1) which is the chancteristic Al (LO) mode of vibration of CdS wurtzite structure, in all samples. The value of the full-width at half-maximum (FWHM) is around 8 cm(-1) for the film grown at 610 degrees C which suggests the good quality of the film obtained. Also the same film gives a yield chi(min) of around 0.048 when it has been probed with Rutherford backscattering spectrometry (RBS) in the c-axis aligned condition, which attests its high degree of crystalline quality. (C) 1999 Elsevier Science S.A. All rights reserved.