Photodissolution of cleaved CdTe(1 1 0): atomic force microscopic and Auger electron spectroscopic study

Presented is the morphological evolution of cleaved CdTe(1 1 0) during photodissolution in 0.1 M Na2SO4 solution. The surfaces of the photodissoluted CdTe(1 1 0) were imaged with an atomic force microscope, and the morphological variation was found to depend on the illumination level. The CdTe(1 1 0) surfaces photodissolved under illumination of ∼0.6 mW/cm2 were covered with homogenously distributed pits and protrusions, and such a morphology was observed consistently within the experimental time scale (2 h). During photodissolution under ∼7 mW/cm2 illumination, however, the morphology varied in a cyclic manner: pit–plateau–protrusion. It has also been found that after two photodissolution cycles, the surface did not show any apparent cyclic behavior. The compositional change of the CdTe(1 1 0) surface illuminated at ∼7 mW/cm2, measured with an Auger electron spectrometer, was observed to correlate with the morphological variation, as well. Based on the correlation of the morphology and composition, the period of the photodissolution cycle under ∼7 mW/cm2 was estimated to be 30 min. The morphological cyclic variation of cleaved CdTe(1 1 0) surface during photodissolution is interpreted in terms of local Te enrichment.