Thin nanodiamond membranes and their microstructural, optical and photoelectrical properties

Abstract

We have grown variety of thin nanocrystalline diamond thin layers on silicon substrates with thicknesses ranging from 100 to 2000 nm. Using a bias enhanced nucleation for nucleation density over 1010 cm-2 and changing the deposition conditions and/or using argon dilution we have obtained nanodiamond layers of different structural properties. The nucleation process and growth was monitored with Scanning Electron Microscopy (SEM); cross-section SEM and micro-Raman measurements were used to access the nanodiamond microstructure. Surface topography was followed by SEM and Atomic Force Microscopy. Windows were opened in the silicon substrate to get self-supporting diamond membrane. Diamond membranes are very smooth, homogeneous and transparent from UV to IR. Fourier Transform Photocurrent Spectroscopy has been used to access main electronic defects in the gap of this material. New defects were observed with photoionization energy of 0.37 and 0.40 eV.