Electronic states of an amorphous semiconductor cluster system: Ge on C

Ultraviolet photoelectron (UPS) and Auger electron (AES) spectroscopies have been applied to study the semiconductor cluster system of Ge on disordered C films. Both UPS and AES reveal that sputtered Ge deposited at 300 K has island growth character. Substantial changes were observed in the valence p states of Ge clusters as the cluster size decreases: the leading edge p-band slope is reduced, the centroid shifts to higher binding energy, and the half-width narrows. These changes are attributed to size effects and an increasing fraction of dangling bonds in the Ge clusters. The form of the UPS spectra suggest amorphous-like order in clusters.