scholarly journals Combined Implications of UV/O3 Interface Modulation with HfSiOX Surface Passivation on AlGaN/AlN/GaN MOS-HEMT

Crystals ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 136
Author(s):  
Soumen Mazumder ◽  
Ssu-Hsien Li ◽  
Zhan-Gao Wu ◽  
Yeong-Her Wang
Keyword(s):  
Plasma Treatment ◽  
Photoelectron Spectroscopy ◽  
Surface Passivation ◽  
Gate Dielectric ◽  
High Electron Mobility Transistors ◽  
Oxide Semiconductor ◽  
Device Performance ◽  
High Electron ◽  
Band Bending ◽  
Current Collapse

Surface passivation is critically important to improve the current collapse and the overall device performance in metal-oxide semiconductor high-electron mobility transistors (MOS-HEMTs) and, thus, their reliability. In this paper, we demonstrate the surface passivation effects in AlGaN/AlN/GaN-based MOS-HEMTs using ultraviolet-ozone (UV/O3) plasma treatment prior to SiO2 -gate dielectric deposition. X-ray photoelectron spectroscopy (XPS) was used to verify the improved passivation of the GaN surface. The threshold voltage (VTH) of the MOS-HEMT was shifted towards positive due to the band bending at the SiO2/GaN interface by UV/O3 surface treatment. In addition, the device performance, especially the current collapse, hysteresis, and 1/f characteristics, was further significantly improved with an additional 15 nm thick hafnium silicate (HfSiOX) passivation layer after the gate metallization. Due to combined effects of the UV/O3 plasma treatment and HfSiOX surface passivation, the magnitude of the interface trap density was effectively reduced, which further improved the current collapse significantly in SiO2-MOS-HEMT to 0.6% from 10%. The UV/O3-surface-modified, HfSiOX-passivated MOS-HEMT exhibited a decent performance, with IDMAX of 655 mA/mm, GMMAX of 116 mS/mm, higher ION/IOFF ratio of approximately 107, and subthreshold swing of 85 mV/dec with significantly reduced gate leakage current (IG) of 9.1 ×10−10 A/mm.

Improved device performance of recessed-gate AlGaN/GaN HEMTs using by in-situ N2O radical treatment

2022 ◽  
Author(s):  
Xinchuang Zhang ◽  
Mei Wu ◽  
Bin Hou ◽  
Xuerui Niu ◽  
Hao Lu ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
High Electron Mobility Transistors ◽  
Device Performance ◽  
High Electron ◽  
Electron Mobility Transistors ◽  
Transmission Electron ◽  
Order Of Magnitude ◽  
Recessed Gate ◽  
Gate Recess

Abstract In this work, the N2O radicals in-situ treatment on gate region has been employed to improve device performance of recessed-gate AlGaN/GaN high-electron-mobility transistors (HEMTs). The samples after gate recess etching were treated by N2O radicals without physical bombardment. After in-situ treatment (IST) processing, the gate leakage currents decreased by more than one order of magnitude compared to the sample without IST. The fabricated HEMTs with the IST process show a low reverse gate current of 10-9 A/mm, high on/off current ratio of 108, and high fT×Lg of 13.44 GHz·μm. A transmission electron microscope (TEM) imaging illustrates an oxide layer with a thickness of 1.8 nm exists at the AlGaN surface. X-ray photoelectron spectroscopy (XPS) measurement shows that the content of the Al-O and Ga-O bonds elevated after IST, indicating that the Al-N and Ga-N bonds on the AlGaN surface were broken and meanwhile the Al-O and Ga-O bonds formed. The oxide formed by a chemical reaction between radicals and the surface of the AlGaN barrier layer is responsible for improved device characteristics.

scholarly journals Performance Enhancement in N2 Plasma Modified AlGaN/AlN/GaN MOS-HEMT Using HfAlOX Gate Dielectric with Γ-Shaped Gate Engineering

Materials ◽  
2021 ◽  
Vol 14 (6) ◽  
pp. 1534
Author(s):  
Shun-Kai Yang ◽  
Soumen Mazumder ◽  
Zhan-Gao Wu ◽  
Yeong-Her Wang
Keyword(s):  
Plasma Treatment ◽  
Leakage Current ◽  
Gate Dielectric ◽  
Device Performance ◽  
High Electron ◽  
Gate Leakage Current ◽  
Surface Plasma ◽  
Gate Leakage ◽  
Transistor Mos ◽  
N2 Plasma

In this paper, we have demonstrated the optimized device performance in the Γ-shaped gate AlGaN/AlN/GaN metal oxide semiconductor high electron mobility transistor (MOS-HEMT) by incorporating aluminum into atomic layer deposited (ALD) HfO2 and comparing it with the commonly used HfO2 gate dielectric with the N2 surface plasma treatment. The inclusion of Al in the HfO2 increased the crystalline temperature (~1000 °C) of hafnium aluminate (HfAlOX) and kept the material in the amorphous stage even at very high annealing temperature (>800 °C), which subsequently improved the device performance. The gate leakage current (IG) was significantly reduced with the increasing post deposition annealing (PDA) temperature from 300 to 600 °C in HfAlOX-based MOS-HEMT, compared to the HfO2-based device. In comparison with HfO2 gate dielectric, the interface state density (Dit) can be reduced significantly using HfAlOX due to the effective passivation of the dangling bond. The greater band offset of the HfAlOX than HfO2 reduces the tunneling current through the gate dielectric at room temperature (RT), which resulted in the lower IG in Γ-gate HfAlOX MOS-HEMT. Moreover, IG was reduced more than one order of magnitude in HfAlOX MOS-HEMT by the N2 surface plasma treatment, due to reduction of N2 vacancies which were created by ICP dry etching. The N2 plasma treated Γ-shaped gate HfAlOX-based MOS-HEMT exhibited a decent performance with IDMAX of 870 mA/mm, GMMAX of 118 mS/mm, threshold voltage (VTH) of −3.55 V, higher ION/IOFF ratio of approximately 1.8 × 109, subthreshold slope (SS) of 90 mV/dec, and a high VBR of 195 V with reduced gate leakage current of 1.3 × 10−10 A/mm.

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