Photoelectrical Properties of Alkali Antimonides

Photoemission, photoconduction and optical absorption of sodium, potassium, rubidium and cesium antimonides were studied at several stages in the course of preparation. In the former three, supply of excess alkali atoms caused the decrease in optical absorption and photoemission at the photon energies higher than the absorption edge, whereas in the last one these phenomena were not remarkable. Photoconduction characteristics were interpreted by assuming two impurity states (donor and acceptor) in each antimonide. At last, two kinds of energy band structures in k -space were proposed on the basis of the crystal structures (cubic and hexagonal), using the energy values obtained from measurements.