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.