Low-temperature epitaxial growth of undoped and n-doped silicon by photochemical vapor deposition using SiH 4/SiH 2Cl 2/H 2/PH 3 mixtures

Abstract

Undoped and doped silicon films were grown epitaxially on (100) substrates of the same material from a gas mixture of dichlorosilane, silane, hydrogen and phosphine, employing mercury-sensitized photochemical vapor deposition (photo-CVD). The films were characterized using reflection high energy electron diffraction (RHEED), Raman spectroscopy, infrared transmittance and electrical measurements. RHEED patterns and Raman measurements revealed the formation of single-crystal silicon films grown at temperatures as low as 150 °C. The best crystallinity was observed on films with a low hydrogen content (calculated from infrared measurements) and was equivalent to that reported previously for photo-CVD films grown from Si 2H 6/SiH 2F 2/H 2 mixtures at lower growth rates. At the phosphine molar fraction 1 × 10 −5 used in this work, the electrical properties of n-doped films are affected in an appreciable manner by hydrogen dilution and temperature.