A new publication provides a universal guideline for the design of Ga2O3 Schottky barrier diodes, and the underlining method has implications for other wide-bandgap semiconductors.
Wenshen Li, Ph.D. student in electrical and computer engineering, is the lead author of the paper published in Applied Physics Letters, titled “Near-ideal reverse leakage current and practical maximum electric field in β-Ga2O3 Schottky barrier diodes.” Devansh Saraswat, Yaoyao Long, Kazuki Nomoto along with Professors Debdeep Jena and Huili Grace Xing are co-authors.
“For the first time, we observed an ideal reverse leakage characteristic in Ga2O3 Schottky barrier diodes,” said Li. “With such information, we can accurately determine how large an electric field can be supported in Ga2O3 Schottky barrier diodes.”
The Schottky diode is a semiconductor diode with a low forward voltage drop capable of rapid switching. It is named after Walter H. Schottky, a German physicist responsible for many significant contributions in the field of semiconductor devices. While a silicon p-i-n diode typically has a forward voltage around 1 V, the Schottky diode counterpart’s forward voltage is much lower, typically below 0.6 V, allowing higher switching speeds and greater system efficiency. The use of the wide-bandgap Ga2O3 material in place of silicon could allow for even better voltage handling capability and efficiency.
“Ideally, a Schottky barrier diode only allows current to flow in one direction when forward biased, and blocks voltage with zero reverse leakage current when reverse biased,” Li explained. “However, in reality, the reverse leakage current is non-zero and increases with the reverse bias, and at some point becomes excessive such that the diode cannot block voltage anymore.“
The new paper seeks to understand how the reverse leakage current behaves under reverse bias, which is crucial for understanding how much voltage a Schottky barrier diode practically can block. To accurately evaluate the reverse blocking capability of the Ga2O3 Schottky barrier diode, the team designed a device in which unwanted extrinsic leakage current is eliminated.
“The devices in the experiment were fabricated in Cornell Nanoscale Facility,” Li said, “and the electrical measurements of these devices were performed in the Jena-Xing lab.”
Their results outline an optimum design for Ga2O3 Schottky barrier diodes, balancing both the on-state voltage drop and reverse blocking capability. “Other researchers will be able to refer to our results for choosing the appropriate Schottky barrier height, depending on the purpose,” Li said.
This paper marks the latest achievement of Li’s academic career in Cornell ECE. He will complete his Ph.D. work with Professor Xing with his thesis defense next month.
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