SURFACE CLEANING WITH HYDROGEN PLASMA FOR LOW-DEFECT-DENSITY ZNSE HOMOEPITAXIAL GROWTH

This article investigates in depth the conditions for cleaning of the (100) ZnSe substrate surface for ZnSe homoepitaxial growth. Wet etchin g with a K2Cr2O7-based etchant as a pre-growth treatment is found to r esult in a Se-rich ZnSe surface that retains its original flatness. Re flection high energy electron diffraction patterns show that plasma ir radiation during thermal cleaning is indispensable for removing the ox ide layer on ZnSe substrate and keeping the flatness. In hydrogen plas ma cleaning, the etch pit density (EPD) of the homoepitaxial film incr eases at rf power higher than 265 W, indicating the optimum cleaning t emperature is between 260 and 280 degrees C. As for the dependence of the EPD on the cleaning time, a minimum EPD of 2.7 x 10(4)/cm(2) can b e obtained for a plasma cleaning time of 20 min. A correlation between the interfacial residual oxygen concentration and the defect density in an epitaxially grown ZnSe film is also found. (C) 1998 American Vac uum Society. [S0734-2101(98)00904-X].