Building Blocks for GaN Power Switches

Estimated reading time: 4 minutes

A team of engineers from Cornell University, the University of Notre Dame and the semiconductor company IQE has created gallium nitride (GaN) power diodes capable of serving as the building blocks for future GaN power switches — with applications spanning nearly all electronics products and electricity distribution infrastructures.

Power semiconductor devices are a critical part of the energy infrastructure — all electronics rely on them to control or convert electrical energy. Silicon-based semiconductors are rapidly approaching their performance limits within electronics, so materials such as GaN are being explored as potential replacements that may render silicon switches obsolete.

But along with having many desirable features as a material, GaN is notorious for its defects and reliability issues. So the team zeroed in on devices based on GaN with record-low defect concentrations to probe GaN’s ultimate performance limits for power electronics. They describe their results in a paper in the journal Applied Physics Letters, from AIP Publishing.

“Our engineering goal is to develop inexpensive, reliable, high-efficiency switches to condition electricity — from where it’s generated to where it’s consumed within electric power systems — to replace generations-old, bulky, and inefficient technologies,” said Zongyang Hu, a postdoc working in Professor Grace Huili Xing’s research group within the School of Electrical and Computer Engineering at Cornell University. “GaN-based power devices are enabling technologies to achieve this goal.”

The team examined semiconductor p-n junctions, made by joining p-type (free holes) and n-type (free electrons) semiconductor materials, which have direct applications in solar cells, light-emitting diodes (LEDs), rectifiers in circuits, and numerous variations in more complex devices such as power transistors. “For our work, high-voltage p-n junction diodes are used to probe the material properties of GaN,” Hu explained.

To describe how much the device’s current-voltage characteristics deviate from the ideal case in a defect-free semiconductor system, the team uses a “diode ideality factor.” This is “an extremely sensitive indicator of the bulk defects, interface and surface defects, and resistance of the device,” he added.

Defects exist within all materials, but at varying levels. “So one parameter we used to effectively describe the defect level in a material is the Shockley-Read-Hall (SRH) recombination lifetime,” Hu said.

Page 1 of 2

• Next Page >