Abstract
Three different insulator layers SiNx, SiON, and SiO2 were used as a gate dielectric and passivation layer in AlGaN/GaN metal–insulator–semiconductor high-electron-mobility transistors (MIS-HEMT). The SiNx, SiON, and SiO2 were deposited by a plasma-enhanced chemical vapor deposition (PECVD) system. Great differences in the gate leakage current, breakdown voltage, interface traps, and current collapse were observed. The SiON MIS-HEMT exhibited the highest breakdown voltage and Ion/Ioff ratio. The SiNx MIS-HEMT performed well in current collapse but exhibited the highest gate leakage current density. The SiO2 MIS-HEMT possessed the lowest gate leakage current density but suffered from the early breakdown of the metal–insulator–semiconductor (MIS) diode. As for interface traps, the SiNx MIS-HEMT has the largest shallow trap density and the lowest deep trap density. The SiO2 MIS-HEMT has the largest deep trap density. The factors causing current collapse were confirmed by Photoluminescence (PL) spectra. Based on the direct current (DC) characteristics, SiNx and SiON both have advantages and disadvantages.
Highlights
In the past decades, the wide bandgap semiconductor material, gallium nitride (GaN), attracted great attention due to its wide bandgap, high breakdown electric field, and excellent thermal properties [1]
The Al2 O3 and HfO2 gate dielectric layer deposited by atomic layer deposition (ALD) has shown advantages in reducing gate leakage and eliminating current collapse [22,23]
The AlGaN/GaN epilayer used in this work is grown on Si (111) substrate using metal–organic chemical vapor deposition (MOCVD)
Summary
The wide bandgap semiconductor material, gallium nitride (GaN), attracted great attention due to its wide bandgap, high breakdown electric field, and excellent thermal properties [1]. Gate leakage current and current collapse are the main issues that limit the performance of AlGaN/GaN high-electron-mobility transistors (HEMTs). To overcome these problems, different dielectric materials have been proposed for the fabrication of metal-insulator-semiconductor (MIS) HEMTs, such as SiO2 [2,3,4,5,6], SiNx [7,8,9,10,11], SiONe [12,13,14], ZrO2 [15], Al2 O3 [16,17,18], and HfO2 [19], etc. The plasma-enhanced chemical vapor deposition (PECVD) is one of the key sectors in conventional GaN-based light emitting diode (LED)
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