Impact of Recess Etching on the Temperature-Dependent Characteristics of GaN-Based MIS-HEMTs With Al2O3/AlN Gate-Stack

This paper studied the recess-etching effects on the temperature-dependent characteristics of AlGaN/GaN metal-insulator-semiconductor high-electron-mobility transistors (MIS-HEMTs) with Al2O3/AlN gate-stack. The 12.6 nm recess-etching resulted in voltage shift of capacitance-voltage curves by 2.4 V, improved peak field-effect mobility ( $\mu _{\text {FE}})$ from 1906 to 2036 cm2/ $\text{V}\cdot \text{s}$ , and increased peak transconductance ( ${g}_{\text {max}})$ from 272 to 353 mS/mm. The temperature-dependent measu-rement from 298 to 473 K showed decrease in maximum drain current, ${g}_{\text {max}}$ , and $\mu _{\text {FE}}$ for both devices with and without recess etching, attributed to thermal electron emission and carrier depletion effects. Recess etching did not degrade the thermal stability of carrier distribution and the transport properties. Temperature-dependent $\mu _{\text {FE}}$ analysis revealed that optical phonon scattering dominated the transport mechanism of Al2O3/AlN/ AlGaN/GaN MIS-HEMTs. Optical phonon energy of 74 and 77 meV were obtained for the devices with and without recess etching, respectively.