Semiconductor Thin Films Grown by Laser Photolysis

Abstract

ABSTRACTThin (< 1.2 μpm) Ge and Si films have been grown with rates up to 3.6 μm/hr by laser-induced chemical vapor deposition (LCVD) on a variety of substrates. Germanium films grown on amorphous SiO2 (quartz) by photodissociating GeH4 in He at 248 nm (KrF laser) exhibit grain sizes of 0.3 – 0.5 μm that increase only slightly up to the pryolytic threshold for GeH4 (280°C). On (100) NaCl, however, Ge films grown at a substrate temperature of 120°C are expitaxial. The activation energy for the LCVD growth of Ge films (from GeH4) on SiO2 is measured to be 85 ± 20 meV which suggests that germanium is arriving at the substrate in atomic form. The wavelength and intensity dependence of the initial film growth rate supports the conclusion that this process is photolytic and is initiated by the absorption of a single photon.