Non-destructive density measurements on thin films of amorphous germanium

Abstract

An in situ method, which is non-destructive, for measuring the densities of thin evaporated films is described. It was used to determine the density of evaporated amorphous germanium films which were prepared on glass and single-crystal sapphire substrates. The substrates were held at room temperature in a conventional vacuum of 10 -6 Torr during the deposition and evaporation rates of 10–20 Å s -1 were used. An 18% density deficit was found for amorphous germanium films on glass substrates, while the densities of films prepared on single-crystal sapphire substrates were essentially (to within experimental error) the same as that of monocrystalline germanium. It is concluded that in order to correlate the measurements of various physical properties of amorphous germanium, it is essential to use the same substrates for all the measurements.