Optical Constants of Germanium in the Region 1 to 10 ev

Abstract

The reflectance, ${|r(\ensuremath{\lambda})|}^{2}$, of single-crystal germanium was measured in the range 0.6 to 11.3 ev. The phase, $\ensuremath{\theta}(\ensuremath{\lambda})$, was computed from these data using the Kramers-Kronig relation between the real and imaginary parts of the complex function $\mathrm{ln}r=\mathrm{ln}|r|+i\ensuremath{\theta}$. The optical constants, $n$ and $k$, were then determined from the Fresnel reflectivity equation. The real part of the refractive index, $n$, has maxima of 5.5 at 2.07 ev and 4.2 at 3.2 ev. Above 6 ev, the index is very nearly 1. The extinction coefficient, $k$, shows maxima of 2.0 at 2.5 ev and 4.2 at 4.4 ev. Below 3.5 ev, the results are in good agreement with the recent measurements of Archer. Beyond this point, they depart from his extrapolated curve.