Lateral Semiconductor-Free-Space Gate Transistors.

Area of Science:

• Materials Science
• Electrical Engineering
• Semiconductor Physics

Background:

• Conventional transistors rely on solid dielectric layers, which can introduce performance limitations due to charge and trap states.
• Wide and ultrawide bandgap semiconductors offer potential for high-power and high-frequency applications but face challenges in device fabrication and performance.

Purpose of the Study:

• To introduce and demonstrate a novel lateral transistor architecture, the semiconductor-free-space gate transistor (SFGT).
• To investigate the feasibility and performance of free-space gating in wide and ultrawide bandgap semiconductors.
• To overcome limitations associated with conventional dielectric layers in transistors.

Main Methods:

• Fabrication of SFGTs with sub-100 nm fin channels and dual side gates, replacing the conventional solid dielectric with a semiconductor-free-space gate configuration.
• Characterization of SFGT performance using β-Ga2O3 as the semiconductor material.
• Evaluation of key transistor parameters including subthreshold slope, drain current, hysteresis, I ON /I OFF ratio, and breakdown voltage.

Main Results:

• Demonstration of free-space gating in wide and ultrawide bandgap semiconductors for the first time.
• SFGTs fabricated with β-Ga2O3 achieved performance comparable to oxide-gated transistors.
• Achieved subthreshold slopes below 200 mV/dec, drain current > 250 mA/mm, hysteresis < 230 mV, I ON /I OFF ratios > 10^6, and breakdown voltages > 500 V.

Conclusions:

• The SFGT architecture offers a promising alternative to conventional transistors by eliminating the solid dielectric layer.
• The open gate geometry allows for direct modulation and threshold voltage tuning, mitigating dielectric-related issues.
• SFGTs show significant potential for advanced memory, sensing, and power applications.