Chemical preparation of CdTe(100) and (110) surfaces using atomic hydrogen

We present the results of an AES, XPS, LEED and photoluminescence study of the reaction of oxide and contaminant overlayers on CdTe(100) and (110) surfaces with atomic hydrogen. For both surfaces exposure of an oxide overlayer to a flux of atomic hydrogen produced by ‘cracking’ ambient molecular hydrogen on a hot tungsten filament results, in contrast to the case of GaAs substrates, in a rapid, quantitative removal of the oxide overlayer at substrate temperatures as low as 300 K. This process results in surfaces free of contaminants which have sufficient surface order to produce clear LEED patterns characteristic of well known reconstructions of these surfaces. Additionally in situ photoluminescence spectroscopy allows direct correlation of surface cleaning with reduced nonradiative carrier recombination.