Grown-film silicon transistors on sapphire

A method was developed for depositing silicon films by the pyrolytic decomposition of SiH
4
on single crystal sapphire. Electron diffraction and Laue reflection examinations of the films shows single-crystal patterns. The silicon film has a Hall mobility of 135 cm
²
/volt-second at a hole density of 10
¹⁷
/cm
³
. Insulated-gate field-effect transistors with a transconductance of 1000 µmho at 5 ma were made with dimensions of 10 µ source-to-drain spacing and an active distance of 120 µ. This value compares favorably with similar units made on bulk silicon and is very encouraging for the possibilities of thin-film silicon devices.