Research on threshold voltage hysteresis of D-mode and fully recessed E-mode AlGaN/GaN MIS-HEMTs with HfO2 dielectric
Depletion-mode (D-mode) and fully recessed enhancement-mode (E-mode) AlGaN/GaN metal-insulator-semiconductor high electron mobility transistors (MIS-HEMTs) with HfO2 dielectric grown by atomic layer deposition (ALD) were fabricated on Si substrates. The threshold voltage hysteresis of D-mode MIS-HEMTs were reduced from 1.11V to 0.42V after post-gate annealing (PGA) at 400℃ in ambient for 5 minutes, which is due to the decrease of the interface-state density (from 8.96*1012-1.2*1014eV-1·cm-2 to 2.6*1012-7.6*1013eV-1·cm-2). By contrasting the threshold voltage hysteresis of D-mode MIS-HEMTs and E-mode MIS-HEMTs after PGA, it is found that the AlGaN/AlN barrier of the D-mode MIS-HEMTs can limited electron flux to the interface, leads to the threshold voltage hysteresis of D-mode MIS-HEMTs is smaller than that of the E-mode MIS-HEMTs.
AlGaN/GaN,high electron mobility transistor (HEMT),atomic layer deposition (ALD),HfO2,interface-state density