Surface barriers formation mechanism of the chemically etched CdTe(111) polar surfaces and gold interfaces

Surface barriers of gold on chemically etched CdTe(111) polar surfaces are studied. Polarities are examined from chemically etched pits patterns with the references. AFM observations of the mirror etched surfaces show the same morphologies on both polarities. Barrier characteristics are evaluated with the current-voltage characteristics. The barriers on (111)A surfaces show nearly ideal Schottky barrier properties but the barriers on (111)B surfaces show the current transport characteristics of recombination preferred properties. XPS analysis on the barrier aged in atmospheric circumstances for one year shows the topmost atomic constitutions as follows. (111)A surfaces are covered with chemically bonded Cd atoms and O atoms. Continuous Ar ion etching intensified signal from Cd atoms and decrease in adsorbed O atoms, but no clear signals from chemically bonded Te atoms are detected. Topmost (111)B surfaces are covered with Cd atoms and chemically bonded Te atoms with O atoms. Continuous Ar ion etching shows more Cd, Te atoms and less adsorbed O atoms. It is considered that the different surface barrier properties of the CdTe(111) are due to the difference of the atomic configurations.