Investigation of AlGaN/GaN Heterostructures Grown on Sputtered AlN Templates with Different Nucleation Layers.

Chuan-Yang Liu,Jin-Cheng Zhang,Sheng-Rui Xu,Li Jiang,Ya-Chao Zhang,Yue Hao

doi:10.3390/ma12244050

Abstract

In this work, a sputtered AlN template is employed to grow high-quality AlGaN/GaN heterostructures, and the effects of AlN nucleation layer growth conditions on the structural and electrical properties of heterostructures are investigated in detail. The optimal growth condition is obtained with composited AlN nucleation layers grown on a sputtered AlN template, resulting in the smooth surface morphology and superior transport properties of the heterostructures. Moreover, high crystal quality GaN material with low dislocation density has been achieved under the optimal condition. The dislocation propagation mechanism, stress relief effect in the GaN grown on sputtered AlN, and metal organic chemical vapor deposition AlN nucleation layers are revealed based on the test results. The results in this work demonstrate the great potential of AlGaN/GaN heterostructures grown on sputtered AlN and composited AlN nucleation layers for microelectronic applications.

Highlights

Group III nitride semiconductors have been demonstrated as promising candidates for optoelectronic and microelectronic applications due to their excellent material properties such as high absorption efficiency, high breakdown field, high thermal conductivity, and high saturated electron drift velocity [1,2,3,4,5,6]
In order to further investigate the effect of the metal organic chemical vapor deposition (MOCVD) AlN nucleation layers (NL) on the surface morphology of the AlGaN/GaN heterostructures, three additional epitaxial samples named as samples D, E, and F
High-quality AlGaN/GaN heterostructures were grown on sputtered AlN templates and the influences of MOCVD AlN NL growth conditions on the structural and electrical properties of the heterostructures were investigated in detail

Summary

Introduction

Group III nitride semiconductors have been demonstrated as promising candidates for optoelectronic and microelectronic applications due to their excellent material properties such as high absorption efficiency, high breakdown field, high thermal conductivity, and high saturated electron drift velocity [1,2,3,4,5,6]. GaN-based heterostructures possess enormous potential for fabricating high-power and high-frequency devices due to the high density and high mobility of two-dimensional electron gas (2DEG) formed by the polarization effect [7,8]. GaN-based heterostructures are commonly grown on foreign substrates (SiC, Si, sapphire, etc.). The large lattice mismatch and thermal expansion coefficients mismatch between the sapphire substrate and the GaN epilayer lead to high dislocation densities and large stress in the growth material. Such issues have motivated the use of various nucleation layers (NL) in the GaN epitaxy on sapphire substrates.

Methods

Results

Conclusion