Photon assisted reduction of interface charge between CdTe substrates and metalorganic chemical vapor deposition CdTe epilayers

A novel photothermal in situ surface pretreatment that reduces the interface charge between p-type CdTe substrates and CdTe epilayers grown by metalorganic chemical vapor deposition is reported. Prior to the actual growth of the epilayers, the substrates are held at 450°C in hydrogen atmosphere and simultaneously exposed to ultraviolet radiation. The interface charge is determined by the modified builtin potential derived from capacitance-voltage characteristics of Schottky contacts formed on the epilayers. The interface charge density is reduced from a typical value of ∼1×10¹² cm^-2 to a practically negligible value.