Chemical vapour deposition of germanium films by laser-induced photolysis of ethylgermanes

Abstract

Excimer laser photolysis of ethylgermanes Et_nGeH_4–n(n= 1–4) at 193 nm yields ethane, ethene and butane along with germanium deposited on the inner surface of the reactor. The distribution of gaseous products is remarkably different from that produced by thermolysis of ethylgermanes and it is attributed to intramolecular elimination of hydrocarbons. The amounts of hydrocarbons formed, as well as the infrared and energy-dispersive X-ray spectra of the solids, reveal that carbon and hydrogen of the ethylgermanes are contained in the volatile photolysis products, while germanium is the dominant element of the deposit. Ethylgermanes are much more prone to photolytic decomposition than germane, which makes them more suitable precursors for photolytic deposition of germanium. The form and morphology of the deposited layers have been investigated.