Electrical properties of InAlN/GaN high electron mobility transistor with Al2O3, ZrO2, and GdScO3 gate dielectrics

Abstract

The authors report on preparation and electrical characterization of InAlN/AlN/GaN metal-oxide-semiconductor (MOS) high electron mobility transistors (HEMTs) with Al2O3, ZrO2, and GdScO3 gate dielectrics. About 10 nm thick high-κ dielectrics were deposited by metal organic chemical vapor deposition after the Ohmic contact processing. Application of the gate dielectrics for 2 μm gate length MOS HEMTs leads to gate leakage current reduction from four to six orders of magnitude compared with Schottky barrier HEMTs. Among others, MOS HEMTs with an Al2O3 gate dielectric shows the highest transconductance (∼150 mS/mm) and maximum drain current (∼0.77 A/mm) and the lowest sheet resistance of ∼260 Ω/◻. MOS HEMTs with GdScO3 shows the highest breakdown electric field of about 7.0 MV/cm. A deep level transient spectroscopy (DLTS) based analysis revealed the maximum interface state density Dit up to 4×1012, 9×1012, and 3×1013 eV−1 cm−2 for Al2O3, ZrO2, and GdScO3/InAlN interface, respectively.