Thermally Enhanced Photoelectric Emission of Reflection-Mode GaAs Photocathode for Solar Energy Conversion: A Theoretical and Experimental Study

Thermally enhanced photoelectric emission (TEPE) from reflection-mode GaAs photocathode, a new technique for solar-energy conversion, was mathematically modeled, theoretically analyzed, numerically simulated and experimentally evaluated. The influence of the cathode's surface electron affinity on the energy conversion efficiency was investigated. The results show that the surface affinity has a major impact. For example, an increasing positive affinity reduces the emission current density and increases the output voltage, affecting the conversion efficiency. The calculated conversion efficiencies, for the negative and positive cathode surface electron affinity, were 15% and over 25%, respectively. As shown in the measurements, an increase of temperature significantly enhanced the spectral sensitivity of reflection-mode GaAlAs/GaAs photodiode, especially in short-wave band. A low work function anode, such as a P-doped diamond film, may result in a conversion efficiency of 2. 7%, slightly increasing with a rise-up of temperature.