Surface State of InP (100) Substrates at Different Stages of A Cleaning

The chemical species present at the surface of InP substrates at the different stages of a classical cleaning (degreasing, etching, de-oxidation and UHV annealing) were studied by infrared absorption (IR). Traces of oxides were detected from nuclear reaction analysis (NRA). With these analysis techniques, after the complete treatment, no defects were revealed at the surface of the substrates. RHEED patterns showed that they were well-reconstructed and SrF 2 thin films were succesfully epitaxially grown on the semiconductor. However, capacitancevoltage (C-V) measurements performed on MIS (SrF 2 /InP) structures showed that to obtain a large modulation of the surface potential of the semiconductor, a sulfurization of the substrates ((NH 4 ) 2 S x ) was required after the etching phase. These results show that many complementary analysis techniques must be used to completely describe the surface state of a cleaned semiconductor.