Effect of an Al-adlayer in the c-plane ZnO/AlN heterostructure

¹ School of Mathematics, China University of Mining and Technology - Xuzhou 221116, China
² School of Physical Science and Technology, China University of Mining and Technology - Xuzhou 221116, China
³ School of Physics, The University of Sydney - Sydney, New South Wales 2006, Australia
⁴ National Lab of Solid State Microstructures, Nanjing University - Nanjing 210093, China

^(a) jlwang@cumt.edu.cn
^(b) catherine.stampfl@sydney.edu.au (corresponding author)

Received: 18 January 2018
Accepted: 23 May 2018

Abstract

The stability and band offsets of ZnO on c-plane AlN substrates with and without an Al-adlayer are studied by first-principles calculations. We determine the ZnO/AlN heterostructure by a layer-by-layer mode from the initial adsorption of the alternative layers of Zn and oxygen atoms of the first ZnO unit cell on c-plane AlN surfaces. The Al-adlayer occupies the top sites of AlN substrates and improves the ordered structure of the grown ZnO. The atomic charges, electronic density of states, and band alignment are systematically analyzed for the optimized ZnO/AlN heterojunction. The Al-adlayer induces in-gap states and causes the decrease of the band offsets for the Zn-terminated ZnO/AlN () heterojunction.