Phase-transition critical thickness of rocksalt MgxZn1-xO layers

Paweł Dłużewski; Jaroslaw Z Domagala; Sławomir Kret; Dawid Jarosz; Marcin Kryśko; Henryk Teisseyre

doi:10.1063/5.0042415

Phase-transition critical thickness of rocksalt Mg_xZn_1-xO layers

J Chem Phys. 2021 Apr 21;154(15):154701. doi: 10.1063/5.0042415.

Authors

Paweł Dłużewski¹, Jaroslaw Z Domagala², Sławomir Kret², Dawid Jarosz², Marcin Kryśko³, Henryk Teisseyre²

Affiliations

¹ Institute of Fundamental Technological Research, Polish Academy of Sciences, ul. Pawińskiego 5b, 02-777 Warszawa, Poland.
² Institute of Physics, Polish Academy of Sciences, Al. Lotników 32/46, 02-668 Warszawa, Poland.
³ Institute of High Pressure Physics, Polish Academy of Sciences, Sokołowska 29/37, 01-142 Warszawa, Poland.

PMID: 33887922
DOI: 10.1063/5.0042415

Abstract

The rocksalt structure of ZnO has a very promising bandgap for optoelectronic applications. Unfortunately, this high-pressure phase is unstable under ambient conditions. This paper presents experimental results for rocksalt-type ZnO/MgO superlattices and theoretical considerations of the critical thickness of Mg_xZn_1-xO layers. The correlations between the layer/spacer thickness ratio, elastic strain, chemical composition, and critical thickness are analyzed. The Matthews and Blakeslee model is revisited to find analytic conditions for the critical layer thickness resulting in phase transition. Our analysis shows that due to the decrease in misfit stresses below some critical limit, the growth of multiple quantum wells composed of rocksalt ZnO layers and MgO spacers is possible only for very large layer/spacer thickness ratios.