Efficient GaN photocathodes for low-level ultraviolet signal detection

We report on the properties of GaN-based photocathodes for low light ultraviolet (UV) signal detection. Cesiated Mg-doped p-type GaN layers with 1-/spl mu/m thickness were used as photocathode materials. Quantum efficiency (QE) as measured on a completed device showed values as high as 30% at 200 nm. A UV/visible rejection ratio of three orders of magnitude at 500 nm was observed. A net increase in the QE was also observed with increasing conductivity of the material.