What is it about?

Better thermal management in demanding applications that require high current density operation for the next generation of power devices is important. For the first time, we demonstrate the laser liftoff (LLO) of AlGaN/GaN HEMTs that were fabricated with >10 µm thick high-quality AlN buffer layers on sapphire substrates. The lifted off layers were then soldered to a copper heat sink to improve their capability to operate at high drain currents without a thermal droop attributed to self-heating. We show that the thermal performance is improved substantially and is like that of devices on bulk SiC substrates, the current gold standard in heat sinks.

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Why is it important?

With the increasing demand for faster and smaller (more power density) electronic devices in both commercial and military applications, the likelihood of higher heat buid-up in electronics is becoming greater. Excessive heat degrades the performance, life, and reliability of power electronics. Therefore, thermal management is becoming more and more pivotal to improve reliability and prevent premature failure. This work demonstrates better thermal management by introducing high thermal conductive thick AlN buffer layer as well as transferring the HEMT structure onto copper heat sink from sapphire by LLO.


It has been a great pleasure to work in Dr. Khan's group to come up with this novel idea for better thermal management in power electronics. I hope this article will pave the way for more efficient power semiconductor devices and opens up a new direction of thermal management by incorporating high thermal conductive epilayer and LLO techniques.

University of South Carolina

Read the Original

This page is a summary of: Excimer laser liftoff of AlGaN/GaN HEMTs on thick AlN heat spreaders, Applied Physics Letters, September 2021, American Institute of Physics,
DOI: 10.1063/5.0064716.
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