High Device Performances and Noise Characteristics of AlGaN/GaN HEMTs Using In Situ SiCN and SiN Cap Layer

Ki-Sik Im,Jin-Seok Choi,Young-Min Hwang,Jae-Seung Roh,Siva Pratap Reddy Mallem,Jae-Hoon Lee,Sung-Jin An

doi:10.3390/nano12040643

Ki-Sik Im, Jin-Seok Choi + Show 5 more

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https://doi.org/10.3390/nano12040643

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Abstract

We fabricated and characterized AlGaN/GaN high-electron mobility transistors (HEMTs) with a nano-sized in situ cap layer (one is a silicon carbon nitride (SiCN) layer, and the other is a silicon nitride (SiN) layer) comparing to the conventional device without an in situ cap layer. The pulse characteristics and noise behaviors for two devices with in situ cap layers are much superior to those of the reference device without a cap layer, which means that the in situ cap layer effectively passivates the AlGaN surface. On the other hand, the device with an in situ SiCN cap layer showed the excellent device characteristics and noise performances compared to the other devices because of the reduced positive ionic charges and enhanced surface morphology caused by carbon (C) surfactant atoms during the growth of the SiCN cap layer. These results indicate that the AlGaN/GaN HEMT with the in situ SiCN cap layer is very promising for the next high-power device by replacing the conventional HEMT.

Highlights

AlGaN/GaN heterostructure exhibits the possibility for applications in high-power and high-frequency electronics [1,2]
We demonstrate two different types of the in situ capped AlGaN/GaN high-electron mobility transistors (HEMTs), one is with in situ SiCN layer, and the other is with in situ SiN layer
The AlGaN/GaN epitaxial structure with various in situ cap layers for the normally-on device operation are grown on 4-inch sapphire substrate by metalorganic chemical vapor deposition (MOCVD)

Summary

Introduction

AlGaN/GaN heterostructure exhibits the possibility for applications in high-power and high-frequency electronics [1,2]. The large conduction band discontinuity and the polarization effects formed at the AlGaN/GaN heterostructure offer large two-dimensional electron gas (2DEG) densities as well as high electron mobility. GaN and its alloy have a great opportunity in view of superior material properties, such as wide energy bandgap and large critical electric field. These advantages allow them to obtain high current density with large breakdown voltage (Vbr ), which is very essential for high output power. One of the major issues is the current collapse phenomenon in AlGaN/GaN-based

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Conclusion