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.