Preparation of InP(100) surface for negative electron affinity photocathode

Atomic hydrogen cleaning is shown to provide a low temperature cleaning mechanism of InP(100) and produces smooth contaminants free surfaces. Reflection high-energy electron diffraction (RHEED) studies show that the InP(100) is 2×4 reconstructed, phosphorus stabilized surface after hydrogen cleaning at 380-400°C. When thermal cleaning is performed up to the congruent temperature, less clear RHEED patterns are obtained as a result of contamination by oxides and carbon compounds. After hydrogen cleaning, activation to negative electron affinity is performed by the adsorption of cesium and oxygen on the surface. These surfaces produce high quantum efficiency (~8.5%), whereas heat cleaned surfaces produce a quantum efficiency of ~0.1%. Atomic hydrogen cleaning is also shown to be effective in reviving the quantum efficiency of negative electron affinity InP(100) photocathode after its degradation