Characterization of the CuGaSe_2/ZnSe Interface Using Kelvin Probe Force Microscopy

摘要

To improve the efficiency of heterostructure solar cells based on chalcopyrite semiconductors a good understanding of the interface properties is crucial. By Kelvin Probe Force Microscopy it is possible to obtain laterally resolved images of the work function of semiconductor surfaces in addition to the topographical information usually obtained by non-contact atomic force microscopy. We studied the CuGaSe_2/ZnSe interface prepared by growth of CuGaSe_2 onto the (110) face of freshly cleaved ZnSe single crystals using chemical vapor deposition. We observed different work function values for different crystal facets on single CuGaSe_2 grains. From the obtained work function data and surface photovoltage measurements a schematic band diagram for the CuGaSe_2/ZnSe heterostructure is proposed.