Photon-enhanced thermionic emission characteristics of Cs deposited Mg-doped InGaN

Abstract The effect of Mg doping on photon-enhanced thermionic emission (PETE) of InGaN emitters was investigated to reduce the high operating temperatures of thermionic energy converters (TECs). Mg-doped In 0.15 Ga 0.85 N enabled TEC operation at 100 °C and enhanced power generation at lower temperatures (100 °C–400 °C). In contrast, In 0.15 Ga 0.85 N without Mg doping required temperatures above 300 °C. Notably, the output power of TEC using Mg-doped In 0.15 Ga 0.85 N was approximately 8.6 times higher at 400 °C than that of InGaN emitter without Mg doping. This enhancement is attributed to Mg doping, which reduces the energy barrier for electron emission and increase the quasi-Fermi level under light irradiation. However, the performance of Mg-doped InGaN decreased at temperatures exceeding 400 °C, due to the limited availability of thermally excited electrons in p-type semiconductors and the increased work function resulting from Cs desorption. Overall, Mg-doped InGaN demonstrates strong potential as a PETE emitter for low-temperature operation and visible-light-driven applications.