Advanced transmission electron microscopy investigation of defect formation in movpe-growth of gap on silicon using arsenic initial coverage

• DOI: 10.1016/j.apsusc.2022.155578
• Publication Date: 2022-11-08T01:54:31Z
• Authors: Amalia Navarro; Elisa García-Tabarés; Quentin M. Ramasse; Pablo Caño; Ignacio Rey-Stolle; Beatriz Galiana
• Keywords: Silicon; HRTEM; EELS; Física; GaP; 02 engineering and technology; Stacking faults; Interface; STEM; MOVPE; Energías Renovables; AsH3; III-V; 0210 nano-technology

This work was supported by the Spanish Ministerio de Ciencia e Innovación through project DAMAINSOL [grant number RTI2018-101020-B-I00], the Regional Government of Madrid through TECHNOFUSIÓN(III)CM (S2018/EMT-4437) and Comunidad de Madrid (Spain) multiannual agreement with UC3M, "Excelencia para el Profesorado Universitario" (EPUC3M14) - Fifth regional research plan 2016-2020. IR-S acknowledges the support provided by the Spanish Ministerio de Ciencia e Innovación through project VIGNEMALE [grant number RTI2018-094291-B-I00]. STEM-EELS was carried out at SuperSTEM, the UK National Facility for Advanced Electron Microscopy, supported by EPSRC.<br/>Integration of GaP layers on silicon substrates using AsH3 pre-exposure followed by a PH3-based GaP epitaxial growth allows the development of very promising processes for the photovoltaic industry, although many of the growth routines using this approach suffer from reproducibility issues when transferred to a new epitaxial system, leading to poor quality layers. This fact reveals a lack of knowledge on the mechanisms behind the formation of the most common planar defects (stacking faults and microtwins) and their dynamics for GaP/Si Metal Organic Vapor Phase Epitaxy using AsH3 and PH3. Therefore, in this work, a set of GaP/Si samples with a similarly high defect density grown between 700 °C and 725 °C, are analyzed by means of high-resolution scanning transmission electron microscopy and electron energy loss spectroscopy. The results presented show contaminant-free Si surfaces for temperatures above 725 °C, ruling out the hypothesis of contaminant as the origin of these planar defects. Regarding the interface Si/GaP, the GaP growth starts, in all the samples, with Gasingle bondSi bonds. Additionally, no traces of As are found, which reinforces the hypothesis of an effectively displacement of As on Si surface by Ga atoms at high temperature. Finally, it is observed complex chemical structures in the origin of the microtwins and the cause of the origin of these defects seems to be a localized gallium depletion at the GaP/Si interface.<br/>