In-situ MOCVD Growth and Band Offsets of Al$_2$O$_3$ Dielectric on $β$-Ga$_2$O$_3$ and $β$-(Al$_x$Ga$_{1-x}$)$_2$O$_3$ thin films

A F M Anhar Uddin Bhuiyan; Lingyu Meng; Hsien-Lien Huang; Jinwoo Hwang; Hongping Zhao

paper

In-situ MOCVD Growth and Band Offsets of Al $_{2}$ O $_{3}$ Dielectric on $β$ -Ga $_{2}$ O $_{3}$ and $β$ -(Al $_{x}$ Ga $_{1 - x}$ ) $_{2}$ O $_{3}$ thin films

arXiv:2207.13001

Abstract

The in-situ metalorganic chemical vapor deposition (MOCVD) growth of Al $_{2}$ O $_{3}$ dielectrics on $β$ -Ga $_{2}$ O $_{3}$ and $β$ -(Al $_{x}$ Ga $_{1 - x}$ ) $_{2}$ O $_{3}$ films is investigated as a function of crystal orientations and Al compositions of $β$ -(Al $_{x}$ Ga $_{1 - x}$ ) $_{2}$ O $_{3}$ films. The interface and film qualities of Al $_{2}$ O $_{3}$ dielectrics are evaluated by high resolution X-ray diffraction (HR-XRD) and scanning transmission electron microscopy (HR-STEM) imaging, which indicate the growth of high quality amorphous Al $_{2}$ O $_{3}$ dielectrics with abrupt interfaces on (010), (100) and (-201) oriented $β$ -(Al $_{x}$ Ga $_{1 - x}$ ) $_{2}$ O $_{3}$ films. The surface stoichiometries of Al $_{2}$ O $_{3}$ deposited on all orientations of $β$ -(Al $_{x}$ Ga $_{1 - x}$ ) $_{2}$ O $_{3}$ are found to be well maintained with a bandgap energy of 6.91 eV as evaluated by high resolution x-ray photoelectron spectroscopy, which is consistent with the atomic layer deposited (ALD) Al $_{2}$ O $_{3}$ dielectrics. The evolution of band offsets at both in-situ MOCVD and ex-situ ALD deposited Al $_{2}$ O $_{3}$ / $β$ -(Al $_{x}$ Ga $_{1 - x}$ ) $_{2}$ O $_{3}$ are determined as a function of Al composition, indicating the influence of the deposition method, orientation, and Al composition of $β$ -(Al $_{x}$ Ga $_{1 - x}$ ) $_{2}$ O $_{3}$ films on resulting band alignments. Type II band alignments are determined at the MOCVD grown Al $_{2}$ O $_{3}$ / $β$ -(Al $_{x}$ Ga $_{1 - x}$ ) $_{2}$ O $_{3}$ interfaces for (010) and (100) orientations, whereas type I band alignments with relatively lower conduction band offsets are observed along (-201) orientation. Results from this work revealed that the in-situ MOCVD deposited high quality Al $_{2}$ O $_{3}$ dielectrics with sharp interfaces can be considered as a viable alternative of commonly used ex-situ deposited (ALD) Al $_{2}$ O $_{3}$ for developing high performance $β$ -Ga $_{2}$ O $_{3}$ and $β$ -(Al $_{x}$ Ga $_{1 - x}$ ) $_{2}$ O $_{3}$ based devices.

In-situ MOCVD Growth and Band Offsets of Al2​O3​ Dielectric on β-Ga2​O3​ and β-(Alx​Ga1−x​)2​O3​ thin films

Abstract

In-situ MOCVD Growth and Band Offsets of Al $_{2}$ O $_{3}$ Dielectric on $β$ -Ga $_{2}$ O $_{3}$ and $β$ -(Al $_{x}$ Ga $_{1 - x}$ ) $_{2}$ O $_{3}$ thin films