Fig. 7
From: Impact of Surface States and Aluminum Mole Fraction on Surface Potential and 2DEG in AlGaN/GaN HEMTs
a Surface potential variation with respect to energy of surface donor trap. At lower concentration (less than 1e14) there is no significant change in surface potential. Surface donor concentration above 1e13, surface potential changing proportionally to the energy of surface donor. b Electron concentration in 2DEG changing from 7.79 × 1011 to 2.75 × 1013 for aluminum percentage changes to 50% from 5% (blue line). Surface potential changes approximately 0.1 eV from 5 to 50% of aluminum percentage