THE OPTICAL PROPERTIES OF THIN GERMANIUM FILMS

The central topic is the deduction of the optical constants from photometric measurements on epitaxial Ge films on CaF2 in the wavelength range 2000 - 6000A. Methods of film production are discussed, and the effect of deposition parameters on the crystallinity and reflectivity of films on fused quartz and CaF2 are reported. The principal conclusion is that epitaxial films give excellent agreement with bulk single crystal material as regards interband transition structure in their reflectivity and transmissivity coefficients R and T. However, the over-all amplitudes of R and T for films are strongly governed by residual surface roughness effects. Theoretical studies are carried out on the accuracy of derivation of the optical constants n and k from measurements of normal incidence R and T on a single film. A review is given of previous investigations and measurements of the optical properties and constants of germanium thin films. (Author)