Transport Properties in GaN Metal-Oxide-Semiconductor Field-Effect Transistor Almost Free of Interface Traps with AlSiO/AlN/p-Type GaN Gate Stack

The factors limiting channel mobility in AlSiO/p-type GaN metal-oxide-semiconductor (MOS) field-effect transistors are examined by performing Hall-effect measurements in conjunction with a gate bias, with and without a thin AlN interlayer. In the absence of this interlayer, the free carrier concentration associated with the Hall effect is significantly reduced compared with the net gate charge density estimated from capacitance-voltage data, indicating that electrons are trapped to a significant extent at the MOS interface. These interface traps are found to have an energy approximate to 20 meV above the Fermi level in strong inversion based on temperature-dependent Hall effect data. The insertion of a 0.8 nm-thick AlN interlayer eliminates charge trapping such that almost all gate charges are mobile. The mobility components could be divided into types based on their effect on the effective electric field perpendicular to the channel. Coulomb scattering centers resulting from interface states are evidently reduced by inserting the AlN interlayer, which also enhances the channel mobility to over 150 cm2 V-1s-1. A transport property of an AlSiO/AlN/p-type GaN metal-oxide-semiconductor field-effect transistor is characterized by gate-biased Hall-effect analyses. The AlN interlayer suppresses electron injection into interface traps, resulting in the ideal free electron conduction. It also reduces Coulomb scattering centers by one-third, which contributes to the high channel mobility over 150 cm2 V-1 s-1.image (c) 2024 WILEY-VCH GmbH