GaN-based complementary inverter logic gate using InGaN/GaN superlattice capped enhancement-mode...

Area of Science:

• Materials Science
• Semiconductor Physics
• Electronics Engineering

Background:

• Gallium Nitride (GaN)-based High Electron Mobility Transistors (HEMTs) show promise for radio-frequency and high-power applications.
• Developing reliable enhancement-mode n-transistors and p-transistors for logic gates remains a significant challenge due to conflicting fabrication requirements.
• Existing methods for n-transistor enhancement-mode operation involve complex techniques like barrier thinning and charged oxides.

Purpose of the Study:

• To propose and analyze a novel GaN-based complementary field-effect transistor device.
• To demonstrate the feasibility of creating both enhancement-mode n-transistors and p-transistors on the same substrate.
• To evaluate the performance of GaN complementary logic gates for high-speed applications.

Main Methods:

• Utilizing a p-doped Indium Gallium Nitride/Gallium Nitride (InGaN/GaN) superlattice (SL) structure on the HEMT heterostructure.
• Analyzing the electrostatic changes induced by the SL, including the formation of a two-dimensional hole gas (2DHG).
• Simulating a digital inverter gate using the proposed complementary transistor structure to assess performance parameters.

Main Results:

• An undoped SL structure effectively converts the n-transistor to enhancement-mode (E-mode) by raising the conduction band-edge.
• The SL structure naturally creates a quantum well for holes, facilitating the p-transistor.
• P-doping the SL further optimizes E-mode n-transistor performance and enhances hole density in the p-transistor.
• Simulations show potential for very high-speed logic operations with low propagation delay.

Conclusions:

• The proposed InGaN/GaN superlattice structure provides a viable pathway for realizing complementary field-effect transistors in GaN.
• This approach overcomes the challenges of fabricating both n- and p-type transistors on a single substrate.
• The developed GaN complementary transistors offer significant potential for next-generation high-speed logic electronics.