Single-Crystalline Si Stacked AlGaN/GaN High-Electron-Mobility Transistors with Enhanced Two-Dimensional Electron Gas...

Area of Science:

• Semiconductor device physics
• Materials science
• Heterojunction engineering

Background:

• High-electron-mobility transistors (HEMTs) rely on a two-dimensional electron gas (2DEG) formed by polarization effects.
• Improving 2DEG density is crucial for enhancing HEMT electrical properties.
• Existing methods for 2DEG modulation present challenges in performance and stability.

Purpose of the Study:

• To investigate the effect of a p-Si nanomembrane on AlGaN/GaN HEMTs.
• To enhance the 2DEG density and improve device performance through surface charge engineering.
• To explore the passivation capabilities of the p-Si layer in HEMTs.

Main Methods:

• Fabrication of a Si/GaN heterojunction using a transferred, heavily boron-doped Si nanomembrane.
• Integration of the p-Si layer on top of AlGaN/GaN HEMTs.
• Electrical characterization to assess device performance metrics like drain current and transconductance.

Main Results:

• The p-Si layer increased surface positive charge, enhancing 2DEG density at the AlGaN/GaN interface by 1.4 times (1.52 × 10^20 cm^-3 to 2.11 × 10^20 cm^-3).
• Maximum drain current improved from 668 mA/mm to 740 mA/mm.
• Maximum transconductance increased from 200.2 mS/mm to 220.4 mS/mm, indicating enhanced device performance.

Conclusions:

• The p-Si nanomembrane effectively increases the 2DEG density in AlGaN/GaN HEMTs.
• The p-Si layer acts as an effective passivation layer, improving device performance.
• This approach offers a promising strategy for developing advanced HEMTs with superior electrical characteristics.