Low Resistance Ohmic Contact on Epitaxial MOVPE Grown β-Ga2O3 and β-(AlxGa1-x)2O3 Films

Article Physics, Applied

4.4 kV β-Ga2O3 MESFETs with power figure of merit exceeding 100 MW cm-2

Arkka Bhattacharyya et al.

Summary: In this paper, beta-Ga2O3 metal-semiconductor field-effect transistors with superior reverse breakdown voltages and ON currents are realized. A special design and etching process are used to enhance its performance.

APPLIED PHYSICS EXPRESS (2022)

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Article Physics, Applied

Highly conductive epitaxial β-Ga2O3 and β-(AlxGa1-x)2O3 films by MOCVD

Fikadu Alema et al.

Summary: We report on the epitaxial growth of highly conductive degenerated Ge or Si doped beta-Ga2O3 and beta-(AlxGa1-x)(2)O-3 films by MOCVD. Record conductivities of 2523 and 1581 S cm(-1) were achieved for highly conductive homoepitaxial beta-Ga2O3 layers using Si and Ge dopants. Highly conductive Si doped beta-(AlxGa1-x)(2)O-3 films were also grown. The incorporation of Si decreased with the increase in Al content and layer thickness. A record high conductivity of 612 S cm(-1) was attained for coherently strained beta-(Al0.12Ga0.88)(2)O-3.

JAPANESE JOURNAL OF APPLIED PHYSICS (2022)

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Article Physics, Applied

130 mA mm-1 β-Ga2O3 metal semiconductor field effect transistor with low-temperature metalorganic vapor phase epitaxy-regrown ohmic contacts

Arkka Bhattacharyya et al.

Summary: The study demonstrates the successful implementation of MOVPE technology for ohmic contacts in OMGBeta-Ga2O3 MESFET, achieving high conductivity and low contact resistance. The fabricated MESFETs show promising performance in terms of current and on/off ratio.

APPLIED PHYSICS EXPRESS (2021)

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Article Engineering, Electrical & Electronic

Multi-kV Class β-Ga2O3 MESFETs With a Lateral Figure of Merit Up to 355 MW/cm2

Arkka Bhattacharyya et al.

Summary: This study presents high-performance over 3 kV gate-pad-connected field plated (GPFP) beta-Ga2O3 lateral MESFETs with high lateral figures of merit (LFOM) achieved through metalorganic vapor phase epitaxy (MOVPE) grown channel layers and regrown ohmic contact layers. By utilizing an improved low-temperature MOVPE selective area epitaxy process, the total contact resistance to the channel has been reduced to as low as 1.4 Omega.mm. The GPFP design utilizing plasma-enhanced chemical vapor deposited (PECVD) SiNx dielectric and SiNx/SiO2 wrap-around passivation demonstrates significant improvements in R-ON and breakdown voltage (V-BR), resulting in up to 3x higher LFOM compared to non-FP beta-Ga2O3 lateral MESFETs. The achieved V-BR (approximately 2.5 kV) and LFOM (355 MW/cm^2) in the GPFP beta-Ga2O3 lateral MESFET are the highest reported values in any depletion-mode beta-Ga2O3 lateral device to date.

IEEE ELECTRON DEVICE LETTERS (2021)

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Review Materials Science, Multidisciplinary

Process and characterization of ohmic contacts for beta-phase gallium oxide

Ming-Hsun Lee et al.

Summary: This study systematically reviews processes for ohmic contact formation on gallium oxide, the contact microstructure, and resulting electrical properties including charge transport physics. It also describes evidence for ohmic contact stability under accelerated aging and proposes alternate ohmic contact materials candidates using thermodynamic assessment. Additionally, gaps in scientific knowledge on ohmic contacts to Ga2O3 are identified and opportunities for future investigations are highlighted.

JOURNAL OF MATERIALS RESEARCH (2021)

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Article Nanoscience & Nanotechnology

Ge doping of β-Ga2O3 by MOCVD

Fikadu Alema et al.

Summary: Ge doping in Ga2O3 was studied using MOCVD epitaxy, where factors influencing the incorporation efficiency of Ge were explored. Results showed that Ge incorporation was strongly dependent on parameters such as GeH4/N-2 flow rate, substrate temperature, and VI/III ratio. The study also found that the choice of Ga precursor and MOCVD reactor geometry played a significant role in the Ge doping process, highlighting challenges in achieving controllable Ge doping for n-type conductivity.

APL MATERIALS (2021)

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Article Engineering, Electrical & Electronic