• Journal of the Korea Institute of Information and Communication Engineering
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• v.16 no.12
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• pp.2741-2746
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• 2012

In this study, we propose a novel structure based on AlGaN substrate or buffer layer to implement a normally-off mode transistor that was difficult to be realized by conventional AlGaN/GaN heterojunction structures. The channel under the gate can be selectively depleted by growing an upper AlGaN barrier with a higher Al mole fraction and a top GaN charge elimination layer on AlGaN substrate or buffer layer. The proposed AlGaN heterojunction field effect transistor can achieve a threshold voltage of > 2 V, which is generally required in power device specification.

• JSTS:Journal of Semiconductor Technology and Science
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• v.16 no.6
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• pp.867-872
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• 2016

We have investigated the channel mobility of AlGaN/GaN-on-Si recessed-metal-oxide-semiconductor-heterojunction field-effect transistors (recessed-MOS-HFET) with $SiO_2$ gate oxide. Both field-effect mobility and effective mobility for the recessed-MOS channel region were extracted as a function of the effective transverse electric field. The maximum field effect mobility was $380cm^2/V{\cdot}s$ near the threshold voltage. The effective channel mobility at the on-state bias condition was $115cm^2/V{\cdot}s$ at which the effective transverse electric field was 340 kV/cm. The influence of the recessed-MOS region on the overall channel mobility of AlGaN/GaN recessed-MOS-HFETs was also investigated.

• JSTS:Journal of Semiconductor Technology and Science
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• v.16 no.2
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• pp.221-225
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• 2016

This paper reports a new method to enable the normally-off operation of AlGaN/GaN heterojunction field-effect transistors (HFETs). A capacitor was connected to the gate input node of a normally-on AlGaN/GaN HFET with a Schottky gate where the Schottky gate acted as a clamping diode. The combination of the capacitor and Schottky gate functioned as a clamp circuit to downshift the input signal to enable the normally-off operation. The normally-off operation with a virtual threshold voltage of 5.3 V was successfully demonstrated with excellent dynamic switching characteristics.

• JSTS:Journal of Semiconductor Technology and Science
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• v.16 no.2
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• pp.215-220
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• 2016

Monolithically integrated devices are strongly desired in next generation power ICs to reduce the chip size and improve the efficiency and frequency response. Three examples of the embedment of different functional diode(s) into AlGaN/GaN heterojunction field-effect transistors are presented, which can minimize the parasitic effects caused by interconnection between devices.