Physical and electrical characteristics of hafnium oxide films on AlGaN/GaN heterostructure grown by pulsed laser deposition

Physical and electrical characteristics of hafnium oxide (HfO2) films grown by pulsed laser deposition (PLD) technique and their application in AlGaN/GaN metal-insulator-semiconductor heterostructure field effect transistors (MIS-HFETs) have been investigated. The PLD-grown amorphous HfO2 films exhibit good constituent uniformity and stoichiometry. The conduction band offset for HfO2/GaN heterostructure is evaluated to be 1.7 eV. The dielectric constant of HfO2 is estimated as ∼ 20 and the effective oxide charge density is ∼ 8.9 × 1011 cm− 2. The fabricated PLD-grown HfO2 MIS-HFETs show a much better electrical performance than the conventional Schottky gate-HFETs, including a larger maximum drain current (31.5%), larger gate voltage swing (8.5%), smaller gate leakage current (two orders of magnitude), and smaller degradation rate at an elevated temperature operation.