A high thermal stability ohmic contact for GaN-based devices.

Area of Science:

• Materials Science
• Semiconductor Physics
• Electrical Engineering

Background:

• Co-integrating gallium nitride (GaN) power devices with silicon (Si) logic ICs enables high-power, high-efficiency single-chip solutions.
• A critical challenge is developing Si-compatible ohmic contacts for GaN devices that withstand high back-end process temperatures.

Purpose of the Study:

• To present an advanced, gold-free ohmic contact with superior thermal stability for AlGaN/GaN high electron mobility transistors (HEMTs).
• To enable reliable co-integration of GaN power devices with Si logic circuits.

Main Methods:

• Fabrication of titanium nitride (TiN) contacts on AlGaN/GaN HEMTs.
• Thermal stability testing at temperatures exceeding 1000 °C.
• Interface chemistry analysis using Scanning Transmission Electron Energy Loss Spectroscopy (STEM EELS).

Main Results:

• The TiN contacts maintained ohmic characteristics and demonstrated exceptional stability at temperatures above 1000 °C.
• STEM EELS analysis revealed enhanced Ga-N and Al-N binding energies and negligible Ti diffusion below 1000 °C.
• The findings clarify the mechanism behind the highly stable ohmic contact formation.

Conclusions:

• A novel, thermally robust, gold-free ohmic contact using TiN has been successfully developed for AlGaN/GaN HEMTs.
• This breakthrough provides a viable pathway for reliable GaN device contacts, crucial for advanced Si/GaN co-integration.
• The study offers new insights into forming stable ohmic contacts for HEMTs and other GaN-based devices.