DC Characteristics of AlGaN/GaN HEMTs Using a Dual-Gate Structure

Area of Science:

• Materials Science
• Semiconductor Physics
• Electrical Engineering

Background:

• AlGaN/GaN-based high-electron-mobility transistors (HEMTs) are crucial for power electronics.
• Modulating the threshold voltage (Vth) is essential for HEMT performance and stability.
• Existing threshold voltage modulation techniques include plasma treatment, p-type gate contacts, and recessed gates.

Purpose of the Study:

• To investigate the effectiveness of a dual-gate structure in modulating the threshold voltage of AlGaN/GaN HEMTs.
• To analyze the impact of the dual-gate design on the two-dimensional electron gas (2DEG) density.
• To compare the performance metrics of dual-gate HEMTs with conventional single-gate HEMTs.

Main Methods:

• Fabrication of dual-gate AlGaN/GaN HEMTs grown on silicon (Si) substrates.
• Experimental characterization of threshold voltage shift in dual-gate versus single-gate devices.
• Analysis of 2DEG density modulation by the second gate.
• Comparative evaluation of maximum drain current, transconductance, and breakdown voltage.

Main Results:

• The dual-gate HEMTs demonstrated a positive shift in threshold voltage, from -4.2 V (single-gate) to -2.8 V.
• The second gate effectively reduced the 2DEG density, contributing to the improved threshold voltage.
• Key performance parameters such as maximum drain current (430 mA/mm vs. 428 mA/mm) and transconductance (83 mS/mm vs. 75 mS/mm) showed no significant degradation.

Conclusions:

• Dual-gate AlGaN/GaN HEMTs provide an effective method for positive threshold voltage modulation.
• The dual-gate approach enhances Vth control without compromising essential device performance.
• This technology holds promise for advanced HEMT applications requiring precise threshold voltage tuning.