GaN/Gr (2D)/Si (3D) Combined High-Performance Hot Electron Transistors

Area of Science:

• Materials Science
• Condensed Matter Physics
• Semiconductor Device Physics

Background:

• Bipolar transistors suffer from minority carrier storage time, limiting switching speed.
• Hot electron transistors (HETs) offer high working speeds and potential for complex logic functions.
• Existing graphene hot electron transistors (GHETs) have limitations in collection efficiency and current saturation.

Purpose of the Study:

• To demonstrate a mixed-dimensional HET utilizing GaN/AlN microwires, graphene, and silicon.
• To achieve high-speed hot electron injection and transport for improved transistor performance.
• To explore the potential of this novel HET architecture for power amplifier applications.

Main Methods:

• Fabrication of a mixed-dimensional HET device comprising GaN/AlN microwires, graphene (Gr), and Si.
• Utilizing Fowler-Nordheim (F-N) tunneling for injecting electrons into graphene.
• Achieving ballistic transport of hot electrons across graphene and low-barrier collection in Si.

Main Results:

• Record DC gain of 16.2 achieved.
• Collection efficiency close to the theoretical limit of 99.9% demonstrated.
• High emitter current density of ~68.7 A/cm² and an on/off current ratio of ~10⁷.
• Wide current saturation range exceeding typical GHETs.

Conclusions:

• The mixed-dimensional HET exhibits excellent performance metrics, including high gain, efficiency, and current ratio.
• The device design overcomes limitations of previous GHETs, particularly in collection efficiency and saturation range.
• This novel HET architecture holds significant promise for advanced electronic applications, especially as power amplifiers.