The band alignment in AlGaN/GaN HEMT devices was investigated using scanning photocurrent microscopy (SPCM) with UV and visible light sources. The polarity of the SPCM on the conduction channel exhibited a switching behavior from p-type to n-type response as the gate bias was increased. The flat-band voltage, which was higher than the DC turn-on voltage, indicates that an ohmic metallic contact was formed for electron transport. We obtained the band offset between the conduction band and the metal Fermi level, which yielded a value of 2.1 eV on average.
This work was supported by the Midcareer Researcher Program (2017R1A2B4009177) through a National Research Foundation grant funded by Korea Government (MSIP) and by Human Resources Program in Energy Technology (20164030201380) of the Korea Institute of Energy Technology Evaluation and Planning (KETEP) grant funded by Korea Government (MOTIE). The research at Korea Advanced Nano Fab Center was supported by Nano∙Material Technology Development Program through the National Research Foundation of Korea funded by Ministry of Science, ICT and Future Planning (2015M3A7B7044548).This work was supported by the Midcareer Researcher Program ( 2017R1A2B4009177 ) through a National Research Foundation grant funded by Korea Government ( MSIP ) and by Human Resources Program in Energy Technology ( 20164030201380 ) of the Korea Institute of Energy Technology Evaluation and Planning ( KETEP ) grant funded by Korea Government ( MOTIE ). The research at Korea Advanced Nano Fab Center was supported by Nano∙Material Technology Development Program through the National Research Foundation of Korea funded by Ministry of Science, ICT and Future Planning ( 2015M3A7B7044548 ).
