INFLUENCE OF HYDROGEN PARTIAL PRESSURE ON DEPOSITION AND PROPERTIES OF SPUTTERED AMORPHOUS GALLIUM ARSENIDE

Thin film of a GaAs H are produced by rf sputtering of a monocrystalline undoped target (ρ ≈ 5 x 107 Ωxcm). We have correlated the hydrogen pressure PH of the discharge with the H concentration CH in the film from nuclear reaction of 15N. Study of growth rate variation with PH shows a decrease from 3 Å/S to about 1 Å/S when hydrogen is added to argon. -a-GaAs-H is strongly absorbent (α > 105 cm-1 at 2 eV). The optical gap E0 increases with PH from 0.91 eV and saturates to 1.45 eV when PH > 40 % of total pressure