Structure and properties of diamond films deposited on porous silicon

Thick porous silicon (PS) layers, made by anodic etching of crystalline Si wafers, have been coated with diamond films using the hot filament chemical vapor deposition (CVD) technique. Ethanol diluted in hydrogen was used as the carbon source for diamond deposition. We observed that diamond nucleati on occurs predominantly on the top of the PS spikes, creating individual is lands of growth. Nucleation is apparently homogeneous over the PS surface a nd the islands grow independently until the complete coalescence of the dia mond film. Although the diamond film is polycrystalline, it does not have t he usual columnar structure of diamond deposited on c-Si. A good adherence between diamond and PS was observed in diamond-Ps and diamond-PS-diamond st ructures. The problems of the intrinsic and thermal stresses have been addr essed. Samples were characterized by atomic force microscopy (AFM), scannin g electron microscopy (SEM), Auger electron spectroscopy (AES), Raman and p hotoluminescence spectroscopy. (C) 1999 Elsevier Science S.A. All rights re served.