/Voltage Surge Capability Study of a E-mode GaN HEMT Device

Voltage Surge Capability Study of a E-mode GaN HEMT Device

Leuven | More than two weeks ago

The objective of this thesis is to study, characterize and analyze the voltage surge capability of IMEC's GaN HEMT devices.

The superior material properties of a gallium nitride (GaN) HEMT leads to a faster, smaller, lighter, and more cost-effective solution and are becoming a serious competitor for Si-based power devices. While these GaN power devices offer great performance, are not well optimized for the protection applications in case of any fault happens. Critical robustness of a power device can be determined by the ability to safely withstand its surge energy. The surge energy indicates how much energy the device can dissipate within itself without triggering catastrophic thermal runway. Surge energy of a Si MOSFET depends on its intrinsic avalanche capability and the parasitic body diode of the MOSFET is responsible for the avalanche rating. During Avalanche conditions, the device behaves like an ideal current source where the current is determined by the series circuit inductance. However, a lateral GaN HEMT do not show any avalanche behaviour due to the absence of a body diode. It exhibits a different surge energy withstand dynamics. The GaN device behaves differently during voltage surge events. It can withstand a transient overvoltage, higher than its rated breakdown voltage.  Its breakdown is expected to be related to a dielectric breakdown caused by the high electric field presented during any surge condition. The GaN device behaves like a voltage source with fixed current during surge events, the drain leakage current remains constant even above the maximum rating of the device.


Imec has developed 100V, 200V and 650V enhancement mode GaN power devices on 200mm Silicon wafers with state-of-the-art performance and reproducibility. The objective of this thesis is to study and characterize the voltage surge capability of our GaN HEMT devices. The candidate will be expected to design and made a test setup of an unclamped inductive switching (UIS) to test the overvoltage capability of the HEMT devices. By using this setup the student needs to characterize how much surge energy the device can withstand during the overvoltage condition. Furthermore, the student will investigate and analyse the different voltage breakdown mechanisms of the GaN device.


Type of work: Literature (10%), Design (30%), Electrical characterization and physical understanding (60%)

Type of project: Thesis, Combination of internship and thesis

Duration: 6-9 months

Required degree: Master of Engineering Technology, Master of Science, Master of Engineering Science

Required background: Electrotechnics/Electrical Engineering, Energy, Nanoscience & Nanotechnology

Supervising scientist(s): For further information or for application, please contact: Urmimala Chatterjee (Urmimala.Chatterjee@imec.be)

Imec allowance will be provided for students studying at a non-Belgian university.

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