Comparison of photoemission performance of AlGaN/GaN photocathodes with different GaN thickness

In view of the different photoemission performance of AlGaN/GaN photocathode with different GaN thickness, three kinds of AlGaN/GaN photocathodes with different GaN layer. The GaN layer thickness of the AlGaN/GaN photocathodes is 7.5 nm, 2 nm and 0 nm. The reflectivity and transmittance has tested, and got absortivity of them. The Cs/O activation results and quantum efficiency fitted results show that AlGaN/GaN photocathodes with a thick GaN layer can achieve higher photoemission and surface electron escape probability, and the quantum efficiency of them is 14.7%, 12.8% and 7.6% at 250 nm. But the UV/solar rejection ratio is increasing along with the thickness of GaN decline. (C) 2013 Elsevier GmbH. All rights reserved.