Electrical Properties of Alkali Antimonides

Systematic studies of the preparation procedures and the electrical characteristics of the alkali antimonides, such as sodium, potassium, rubidium and cesium antimonides, were carried out. It has been found that these antimonides can be classified into two groups, i.e., a group which transits from p -type to n -type with successive activation, e.g. sodium and potassium antimonides, and a group which keeps constantly p -type, e.g. cesium antimonide. Rubidium antimonide was recognized to be an intermediate compound lying between these two groups. Supply of excess alkali metal, deposition of additional antimony and superficial oxidation gave remarkable effects on the dark and photoconductivity and the photoemission, but these effects proceeded in opposite derections in these two groups. With decreasing temperature, the mobility of n -type compound decreased, whereas that of p -type one increased. A picture of impurity states in these compounds was proposed in order to interprete the above mentioned phenomena, taking the ionic radius of alkali atom and the crystal structure into consideration.