Electron-Hole Pair Creation in Gallium Phosphide by α Particles

Abstract

The energy required to form one hole-electron pair in gallium phosphide has been measured to be 7.8±0.8 eV/pair. The experimental method consisted of determining the charge produced and collected when α particles of known energy bombarded a surface barrier which had been formed by evaporating a thin layer of gold onto an etched surface of the gallium phosphide. When high-resistivity gallium phosphide (produced by copper diffusion) was used, the α-particle detection efficiency dropped very sharply but could be restored to almost unity efficiency by illumination. This effect is attributed to the action of traps on the charge collection process.