Quantum efficiency characteristics of low-threading-dislocation-density InGaN photocathode grown on GaN substrate Available to Purchase

The dependence of the quantum efficiency (QE) of a Cs/O-activated negative-electron-affinity (NEA) state InGaN photocathode on threading dislocation density (TDD) was investigated. InGaN photocathodes with different TDDs were grown on sapphire and GaN substrates by metal-organic vapor-phase epitaxy (MOVPE). The TDDs were 1 × 10⁹ cm⁻² on the sapphire substrate and less than 5 × 10⁶ cm⁻² on the GaN substrate. After the activation of the NEA state of InGaN photocathode surfaces by Cs/O, the QEs were 1.1% on the sapphire substrate and 0.91% on the GaN substrate. Despite a TDD difference of approximately two orders of magnitude, the QEs were comparable. The results show that the QE is not limited by the high TDD in the InGaN photocathode.