Surface activation of n-type AlGaN with cesium and oxygen to enhance thermionic emission

Abstract The paper describes the characteristics of thermionic emission of AlGaN surface through surface control employing cesium (Cs) and oxygen. The thermionic emission current of AlGaN surfaces with Cs and oxygen was measured, and the surface state of AlGaN was analyzed by employing a new material-independent thermionic emission model (MRM) based on the Richardson-Dushman equation successfully reproduced the thermionic emission behavior of Cs-deposited and Cs/O2 co-deposited AlGaN, considering the dynamic change of the surface layer caused by thermal desorption of Cs. These results indicate that AlGaN co-deposited with Cs/O2 could be applied as a thermionic energy converter operating in a lower to medium temperature range (200-800 °C), as compared to conventional devices.