CONTROLLING SURFACES AND INTERFACES OF SEMICONDUCTORS USING ORGANIC-MOLECULES

Control over semiconductor surface energetics can be achieved using di fferent chemisorbed organic molecules with diverse electronic properti es. We find evidence of such control over CdTe upon adsorption of dica rboxylic acid derivatives with different substituted phenyl rings. FT- IR measurements show that the dicarboxylic acid derivatives bind as ca rboxylates to form approximately one monolayer. Such chemisorption mod ifies both the band bending and the electron affinity (up to 500 and 7 00 mV, respectively), as measured by contact potential difference (CPD ). Changes in band bending result from a coupling between molecular or bitals and surface states close to the valence band and depend on the withdrawing character of the phenyl substituent. A model is presented to interpret and explain the data. (C) 1998 Elsevier Science B.V.