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 has focused on devices based on GaN with record-low defect concentrations to probe GaN's performance limits for power electronics.
"Our engineering goal is to develop inexpensive, reliable, high-efficiency switches to condition electricity to replace generations-old, bulky, and inefficient technologies," said Zongyang Hu, a researcher at the School of Electrical and Computer Engineering, 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 and n-type semiconductor materials, which have direct applications in solar cells, LEDs, rectifiers in circuits, and numerous variations in more complex devices such as power transistors.
To describe how much the device's current-voltage characteristics deviate from the ideal case in a defect-free semiconductor system, the team used a ‘diode ideality factor’: "an extremely sensitive indicator of the bulk defects, interface and surface defects, and resistance of the device," Hu explained.
The work by Cornell University is the first report of GaN p-n diodes with near-ideal performance in all aspects simultaneously: a unity ideality factor, avalanche breakdown voltage, and about a two-fold improvement in device figure-of-merits over previous records.
"Our results are an important step toward understanding the intrinsic properties and the true potential of GaN," Hu added.
