A Novel GaN:C Millimeter-Wave HEMT with AlGaN Electron-Blocking Layer

Area of Science:

• Semiconductor Device Physics
• Materials Science
• Microwave Engineering

Background:

• High electron mobility transistors (HEMTs) are crucial for high-frequency applications.
• Gallium Nitride (GaN) based HEMTs offer superior performance compared to traditional materials.
• Optimizing buffer layers and device structures is key to enhancing HEMT performance.

Purpose of the Study:

• To investigate the performance of an AlGaN/GaN/Si HEMT with a GaN:C buffer and a 2 nm AlGaN electron-blocking layer (EBL) for millimeter-wave applications.
• To compare the proposed HEMT structure with the double heterostructure field effect transistor (DHFET).
• To evaluate the impact of the AlGaN EBL on device characteristics like leakage, thermal stability, and electron confinement.

Main Methods:

• Fabrication of AlGaN/GaN/Si HEMTs incorporating a GaN:C buffer and a 2 nm AlGaN EBL.
• Characterization of device performance, including vertical leakage, thermal stability, and radio frequency (RF) performance.
• Analysis of electron confinement in the two-dimensional electron gas (2DEG) and mitigation of carbon-related traps.

Main Results:

• The AlGaN/GaN HEMT with the GaN:C/EBL buffer demonstrated lower vertical leakage and higher thermal stability than DHFETs.
• Improved RF performance was observed in the novel HEMT structure.
• The AlGaN EBL effectively suppressed carbon-related traps and enhanced electron confinement in the 2DEG.
• A maximum output power (Pout) of 31.2 dBm and a power added efficiency (PAE) of 21.7% were achieved at 28 GHz and 28 V.

Conclusions:

• The developed AlGaN/GaN/Si HEMT with a GaN:C buffer and AlGaN EBL shows significant potential for millimeter-wave applications.
• The integration of GaN:C buffer and AlGaN EBL epitaxy technology offers a promising pathway for advanced high-frequency devices.
• This technology advancement contributes to the development of more efficient and stable millimeter-wave systems.