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An Overview of Normally-Off GaN-Based High Electron Mobility Transistors

Consiglio Nazionale delle Ricerche—Istituto per la Microelettronica e Microsistemi (CNR-IMM) Strada VIII, n. 5-Zona Industriale, Catania 95121, Italy
STMicroelectronics, Stradale Primosole 50, Catania 95121, Italy
Author to whom correspondence should be addressed.
Materials 2019, 12(10), 1599;
Received: 16 April 2019 / Revised: 8 May 2019 / Accepted: 14 May 2019 / Published: 15 May 2019
PDF [2531 KB, uploaded 17 May 2019]


Today, the introduction of wide band gap (WBG) semiconductors in power electronics has become mandatory to improve the energy efficiency of devices and modules and to reduce the overall electric power consumption in the world. Due to its excellent properties, gallium nitride (GaN) and related alloys (e.g., AlxGa1−xN) are promising semiconductors for the next generation of high-power and high-frequency devices. However, there are still several technological concerns hindering the complete exploitation of these materials. As an example, high electron mobility transistors (HEMTs) based on AlGaN/GaN heterostructures are inherently normally-on devices. However, normally-off operation is often desired in many power electronics applications. This review paper will give a brief overview on some scientific and technological aspects related to the current normally-off GaN HEMTs technology. A special focus will be put on the p-GaN gate and on the recessed gate hybrid metal insulator semiconductor high electron mobility transistor (MISHEMT), discussing the role of the metal on the p-GaN gate and of the insulator in the recessed MISHEMT region. Finally, the advantages and disadvantages in the processing and performances of the most common technological solutions for normally-off GaN transistors will be summarized. View Full-Text
Keywords: gallium nitride; normally-off HEMT; power electronics gallium nitride; normally-off HEMT; power electronics

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Roccaforte, F.; Greco, G.; Fiorenza, P.; Iucolano, F. An Overview of Normally-Off GaN-Based High Electron Mobility Transistors. Materials 2019, 12, 1599.

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