Core Transitions and Density of Conduction States in the III-V Semiconductors

The absorption and reflection spectra of several amorphous and crystalline III-V semiconductors have been measured in the region from 10 to 30 eV where transitions from the outermost $d$ levels of the cation cores occur. The use of the continuous spectrum of synchrotron radiation of DESY enabled us to resolve considerable structure in the crystalline samples. This structure can be interpreted as due to structure in the density of conduction states and to the spin-orbit splitting of the core level.