Diamond surface conductivity experiments and photoelectron spectroscopy

A unique feature of diamond surfaces is a highly conductive p-type layer wh ich is usually observed when the surfaces are hydrogen terminated. We prese nt a combination of conductivity and photoelectron yield measurements on a variety of different diamond samples in order to elucidate the role of hydr ogen and adsorbates for this phenomenon. The experiments show that hydrogen termination is a necessary but not a sufficient condition for the appearan ce of the surface conductivity. Additionally, adsorbates from the atmospher e are needed. On the basis of the experiments an electrochemical model is d eveloped which can explain the effect of the hydrogen termination and also shows why hydrogen terminated diamond is the only semiconductor with p-type surface conductivity. (C) 2001 Elsevier Science B.V. All rights reserved.