Classification of charge relaxation processes in diamond on silicon based devices

摘要

Diamond thin films on p-type Si prepared via a bias enhanced chemical vapor deposition technique and equipped with Al Schottky contacts are studied by charge deep-level transient spectroscopy.Three charge relaxation processes can be resolved in Q-DLTS spectra:(i)a spectrum of relaxation times centered about a thermal energy of 0.33 eV has been assigned to hole traps induced by Al/diamond interface dipoles.These are metastable when heating the diodes to 450 K during a Q-DLTS scan,(ii)quasi discrete energy levels at 0.82 and 0.98 eV are indicative of an amorphous (hydrogenated)Si (a-Si:H)interlayer between the Si substrate and diamond film.This conclusion results from a direct comparison with Q-DLTS spectra of a-Si:H based devices and (iii)a slow charge relaxation with a non-exponential kinetics responsible for a Q-DLTS signal tail independent of the rate window for longer times of observation.This phenomenon is known from frequency-domain observations as 'nearly constant loss'.