Photoemission from Cesium Oxide Covered GaInAs

Abstract

White light photoresponse, quantum efficiency, energy distribution, work function, dark current, uniformity, and stability of the photoresponse of GaInAs were measured at room temperature. The polycrystalline, heavily doped p‐type samples were polished, glow discharged, heat cleaned in an ultrahigh vacuum system and covered with cesium oxide. The photoemission up to photon energies of 1.85 eV is due to thermalized photoelectrons that diffuse in the Γ_1C conduction band minimum. Their diffusion length and escape probability were evaluated. Above 1.85 eV, electrons thermalized in the X_1C and L_1C conduction band minima and hot electrons contributed considerably to the photoemissive yield. Work function measurements by the vibrating reed method showed that the threshold at 1.05 eV was bandgap limited. Stability and uniformity studies indicated a great potential for the application of this material as a practical photocathode.