Strain Analysis of GaN HEMTs on (111) Silicon with Two Transitional AlxGa1-xN Layers.

Yuefei Cai,Xiang Yu,Chenqi Zhu,Tao Wang,Volkan Esendag,Ling Jiu,Yipin Gong,Jie Bai

doi:10.3390/ma11101968

Abstract

We have designed and then grown a simple structure for high electron mobility transistors (HEMTs) on silicon, where as usual two transitional layers of AlxGa1−xN (x = 0.35, x = 0.17) have been used in order to engineer the induced strain as a result of the large lattice mismatch and large thermal expansion coefficient difference between GaN and silicon. Detailed x-ray reciprocal space mapping (RSM) measurements have been taken in order to study the strain, along with cross-section scanning electron microscope (SEM) images and x-ray diffraction (XRD) curve measurements. It has been found that it is critical to achieve a crack-free GaN HEMT epi-wafer with high crystal quality by obtaining a high quality AlN buffer, and then tuning the proper thickness and aluminium composition of the two transitional AlxGa1−xN layers. Finally, HEMTs with high performance that are fabricated on the epi-wafer have been demonstrated to confirm the success of our strain engineering and above analysis.

Highlights

In the last decade, III-nitride devices have been widely used in many applications, such as general illumination [1], radio-frequency communication [2] and power conversion [3], etc
Crossscanning electron microscope (SEM, Raith, Dortmund, Germany) measurements have been taken as sectional scanning electron microscope (SEM, Raith, Dortmund, Germany) measurements have been shown in Figure 2a,b, taken from the central part and the edge part, respectively, indicating that the taken as shown in Figure 2a,b, taken from the central part and the edge part, respectively, indicating thicknesses for the AlN buffer layer, the Al0.35 Ga0.65 N layer, the Al0.17 Ga0.83 N layer and the GaN layer that the thicknesses for the AlN buffer layer, the Al0.35Ga0.65N layer, the Al0.17Ga0.83N layer and the GaN
We have achieved a crack-free GaN high electron mobility transistors (HEMTs) epi-wafer grown on silicon by properly

Summary

Introduction

III-nitride devices have been widely used in many applications, such as general illumination [1], radio-frequency communication [2] and power conversion [3], etc. For electronic applications, GaN high electron mobility transistors (HEMTs) are expected to demonstrate a number of major advantages, such as a fast switching speed, low switching loss and high power conversion efficiency in comparison with silicon based counterparts [4]. The idea is to use the compressive strain that is built due to the GaN on these Al(Ga)N layers to compensate the tensile strain between GaN and silicon generated during the post-growth cooling down process.

Methods

Results

Conclusion