We have calculated first excitation energies, oscillator strengths, and potential energy surfaces of B2H6 and PH3 by using an ab initio molecular orbital method to confirm that the deuterium lamp is effective for the excitation of both B2H6 and PH, in the photo-chemical vapor deposition (photo-CVD) process. The deuterium lamp is useful for growing the film at 600-1000 degreesC in the B2H6-PH3-H-2 system. The activation energies for film growth for thermal CVD decrease by using the deuterium lamp. Boron phosphide film grew epitaxially on Si(100) plane with a deuterium lamp at lower temperature than by thermal CVD at 100 degreesC, The electrical properties of boron and boron phosphide films on silica glass were improved by deuterium, (C) 2000 Academic Press.