Positron beam characterisation of a CVD-grown diamond thick film

A composite structure consisting of a thick chemical vapour deposition (CVD ) polycrystalline diamond layer grown on an aluminium substrate, covered wi th a thin gold cap layer has been studied using positron beam and other tec hniques. The diamond layer has a strong [110] texture and also contains sma ll fractions of aluminium carbide and graphitic phases. Positron beam analy sis reveals two states, corresponding to a highly defective thin gold layer and an homogeneous diamond layer with large, essentially defect free, crys tallites. (C) 1999 Elsevier Science B.V. All rights reserved.