Drastically enhanced cation incorporation in the epitaxy of oxides due to formation and evaporation of suboxides from elemental sources

In the molecular beam epitaxy of oxide films, the cation (Sn, Ga) or dopant (Sn) incorporation does not follow the vapor pressure of the elemental metal sources but is enhanced by several orders of magnitude for low source temperatures. Using line-of-sight quadrupole mass spectrometry, we identify t...

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Autores principales:	Georg Hoffmann, Zongzhe Cheng, Oliver Brandt, Oliver Bierwagen
Formato:	article
Lenguaje:	EN
Publicado:	AIP Publishing LLC 2021
Materias:	Biotechnology TP248.13-248.65 Physics QC1-999
Acceso en línea:	https://doaj.org/article/aaaefc0d72a84e28b136b876393218d9
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spelling	oai:doaj.org-article:aaaefc0d72a84e28b136b876393218d92021-12-01T18:51:23ZDrastically enhanced cation incorporation in the epitaxy of oxides due to formation and evaporation of suboxides from elemental sources2166-532X10.1063/5.0058541https://doaj.org/article/aaaefc0d72a84e28b136b876393218d92021-11-01T00:00:00Zhttp://dx.doi.org/10.1063/5.0058541https://doaj.org/toc/2166-532XIn the molecular beam epitaxy of oxide films, the cation (Sn, Ga) or dopant (Sn) incorporation does not follow the vapor pressure of the elemental metal sources but is enhanced by several orders of magnitude for low source temperatures. Using line-of-sight quadrupole mass spectrometry, we identify the dominant contribution to the total flux emanating from Sn and Ga sources at these temperatures to be due to the unintentional formation and evaporation of the respective suboxides SnO and Ga2O. We quantitatively describe this phenomenon by using a rate-equation model that takes into account the O2 background pressure, the resulting formation of the suboxides via oxidation of the metal source, and their subsequent thermally activated evaporation. As a result, the total flux composed of the metal and the suboxide fluxes exhibits an S-shaped temperature dependence instead of the expected linear one in an Arrhenius plot, which is in excellent agreement with the available experimental data. Our model reveals that the thermally activated regimes at low and high temperatures are almost exclusively due to suboxide and metal evaporation, respectively, joined by an intermediate plateau-like regime in which the flux is limited by the available amount of O2. An important suboxide contribution is expected for all elemental sources whose suboxide exhibits a higher vapor pressure than that of the element, such as B, Ga, In, La, Si, Ge, Sn, Sb, Mo, Nb, Ru, Ta, V, and W. This contribution can play a decisive role in the molecular beam epitaxy of oxides, including multicomponent or complex oxides, from elemental sources. Finally, our model predicts suboxide-dominated growth in low-pressure chemical vapor deposition of Ga2O3 and In2O3.Georg HoffmannZongzhe ChengOliver BrandtOliver BierwagenAIP Publishing LLCarticleBiotechnologyTP248.13-248.65PhysicsQC1-999ENAPL Materials, Vol 9, Iss 11, Pp 111110-111110-10 (2021)
institution	DOAJ
collection	DOAJ
language	EN
topic	Biotechnology TP248.13-248.65 Physics QC1-999
spellingShingle	Biotechnology TP248.13-248.65 Physics QC1-999 Georg Hoffmann Zongzhe Cheng Oliver Brandt Oliver Bierwagen Drastically enhanced cation incorporation in the epitaxy of oxides due to formation and evaporation of suboxides from elemental sources
description	In the molecular beam epitaxy of oxide films, the cation (Sn, Ga) or dopant (Sn) incorporation does not follow the vapor pressure of the elemental metal sources but is enhanced by several orders of magnitude for low source temperatures. Using line-of-sight quadrupole mass spectrometry, we identify the dominant contribution to the total flux emanating from Sn and Ga sources at these temperatures to be due to the unintentional formation and evaporation of the respective suboxides SnO and Ga2O. We quantitatively describe this phenomenon by using a rate-equation model that takes into account the O2 background pressure, the resulting formation of the suboxides via oxidation of the metal source, and their subsequent thermally activated evaporation. As a result, the total flux composed of the metal and the suboxide fluxes exhibits an S-shaped temperature dependence instead of the expected linear one in an Arrhenius plot, which is in excellent agreement with the available experimental data. Our model reveals that the thermally activated regimes at low and high temperatures are almost exclusively due to suboxide and metal evaporation, respectively, joined by an intermediate plateau-like regime in which the flux is limited by the available amount of O2. An important suboxide contribution is expected for all elemental sources whose suboxide exhibits a higher vapor pressure than that of the element, such as B, Ga, In, La, Si, Ge, Sn, Sb, Mo, Nb, Ru, Ta, V, and W. This contribution can play a decisive role in the molecular beam epitaxy of oxides, including multicomponent or complex oxides, from elemental sources. Finally, our model predicts suboxide-dominated growth in low-pressure chemical vapor deposition of Ga2O3 and In2O3.
format	article
author	Georg Hoffmann Zongzhe Cheng Oliver Brandt Oliver Bierwagen
author_facet	Georg Hoffmann Zongzhe Cheng Oliver Brandt Oliver Bierwagen
author_sort	Georg Hoffmann
title	Drastically enhanced cation incorporation in the epitaxy of oxides due to formation and evaporation of suboxides from elemental sources
title_short	Drastically enhanced cation incorporation in the epitaxy of oxides due to formation and evaporation of suboxides from elemental sources
title_full	Drastically enhanced cation incorporation in the epitaxy of oxides due to formation and evaporation of suboxides from elemental sources
title_fullStr	Drastically enhanced cation incorporation in the epitaxy of oxides due to formation and evaporation of suboxides from elemental sources
title_full_unstemmed	Drastically enhanced cation incorporation in the epitaxy of oxides due to formation and evaporation of suboxides from elemental sources
title_sort	drastically enhanced cation incorporation in the epitaxy of oxides due to formation and evaporation of suboxides from elemental sources
publisher	AIP Publishing LLC
publishDate	2021
url	https://doaj.org/article/aaaefc0d72a84e28b136b876393218d9
work_keys_str_mv	AT georghoffmann drasticallyenhancedcationincorporationintheepitaxyofoxidesduetoformationandevaporationofsuboxidesfromelementalsources AT zongzhecheng drasticallyenhancedcationincorporationintheepitaxyofoxidesduetoformationandevaporationofsuboxidesfromelementalsources AT oliverbrandt drasticallyenhancedcationincorporationintheepitaxyofoxidesduetoformationandevaporationofsuboxidesfromelementalsources AT oliverbierwagen drasticallyenhancedcationincorporationintheepitaxyofoxidesduetoformationandevaporationofsuboxidesfromelementalsources
_version_	1718404712820113408

Drastically enhanced cation incorporation in the epitaxy of oxides due to formation and evaporation of suboxides from elemental sources

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