STOICHIOMETRY OF THE DIAMOND SILICON INTERFACE AND ITS INFLUENCE ON THE SILICON CONTENT OF DIAMOND FILMS/

Thin films of diamond were grown by microwave plasma chemical vapor de position at growth pressures of 10, 20, 40, and 60 Torr keeping the su bstrate temperature constant at 975 degrees C. Increase in the growth pressure reduced the size of the plasma ball resulting in an increase in the microwave power density (MPD). The films were characterized by scanning electron microscopy, micro-Raman, and photoluminescence (PL) spectroscopy. A systematic variation was observed in surface morpholog y and quality of the films. The intensity of the peak at 1.68 eV in th e PL spectra of the films, which is assigned to Si impurities was also observed to increase consistently with the MPD. The stoichiometry of the diamond/silicon interface was studied by x-ray photoelectron spect roscopy (XPS) and found to be a sensitive function of the MPD. XPS res ults showed the formation of nonstoichiometric SiC along with other ca rbon phases in the initial stages of the growth. A correlation was obs erved between the composition of the interface and the intensity of th e 1.68 eV peak. The above results are explained in terms of the increa se in the impingement flux density of atomic hydrogen with the MPD. (C ) 1998 American Institute of Physics.