N-type phosphorus-doped polycrystalline diamond on silicon substrates

Abstract

The microwave plasma-assisted deposition of reproducible and homogeneously n-type phosphorus-doped polycrystalline (microcrystalline) diamond films on silicon substrates is described. The phosphorus incorporation is obtained by adding gaseous phosphine (PH 3) to the gas mixture during growth. The low CH 4/H 2 ratio (0.15%) and the use of the same growth parameters as for homoepitaxial {111} films, led to a good crystalline quality of the continuous polycrystalline diamond layers, confirmed by SEM images and Raman spectroscopy measurements. Secondary-ion mass spectrometry (SIMS) analysis measured a phosphorus concentration [P] of at least 7 × 10 17 cm − 3 . Cathodoluminescence spectroscopy in our P-doped polycrystalline films shows a phosphorus bound exciton (BE TO P) peak between 5.142 and 5.181 eV. Cathodoluminescence and Raman-effect spectroscopy confirmed the improvement of the crystalline quality of our films as well as a decrease in the intensity of the internal strain when the grain size was decreased. Cathodoluminescence imaging and SIMS depth profile of phosphorus demonstrated a very good homogeneity of phosphorus incorporation in the films.