Low-temperature growth of polycrystalline Si and Ge films by ultraviolet laser photodissociation of silane and germane

Polycrystalline Si and Ge films have been grown on amorphous SiO2 substrates (average Tsubstrate <120 °C) by the photodissociation of SiH4/N2 or GeH4/He mixtures, respectively, using pulsed ArF (193 nm) and KrF (248 nm) excimer lasers. For both Si and Ge, the film growth rate exhibited a strong dependence on laser wavelength and beam intensity I, where 1≲I⩽20 MW cm−2. As-deposited films exhibited average grain sizes of up to 0.5 μm and the grains were equiaxed with a random orientation. Ge films doped with ∼1020 cm−3 Al were obtained by the simultaneous photodissociation of Al(CH3)3 and GeH4.