Monolayer Doping of Silicon-Germanium Alloys: a Balancing Act between Phosphorus Incorporation and Strain Relaxation

Authors

Noel Kennedy, School of Chemistry, University College Cork, Cork, T12 YF78, Ireland; Tyndall National Institute, Lee Maltings, Cork T12 R5CP, Ireland; CRANN@AMBER, Trinity College Dublin, Dublin 2, D02 E16, Ireland
Ray Duffy, Tyndall National Institute, Lee Maltings, Cork, T12 R5CP, Ireland
Gioele Mirabelli, Tyndall National Institute, Lee Maltings, Cork, T12 R5CP, Ireland
Luke Eaton, School of Chemistry, University College Cork, Cork, T12 YF78, Ireland; Tyndall National Institute, Lee Maltings, Cork T12 R5CP, Ireland; CRANN@AMBER, Trinity College Dublin, Dublin 2, D02 E16, Ireland
Nikolay Petkov, Cork Institute of Technology, Bishopstown, Cork, IrelandFollow
Justin D. Holmes, School of Chemistry, University College Cork, Cork, T12 YF78, Ireland; Tyndall National Institute, Lee Maltings, Cork T12 R5CP, Ireland; CRANN@AMBER, Trinity College Dublin, Dublin 2, D02 E16, Ireland
Chris Hatem, Applied Materials, Gloucester, Massachusetts, MA 01930, USA
Lee Walsh, Tyndall National Institute, Lee Maltings, Cork, T12 R5CP, Ireland
Brenda Long, School of Chemistry, University College Cork, Cork, T12 YF78, Ireland; Tyndall National Institute, Lee Maltings, Cork T12 R5CP, Ireland; CRANN@AMBER, Trinity College Dublin, Dublin 2, D02 E16, Ireland

ORCID

https://orcid.org/0000-0002-5539-9595

Document Type

Article

Disciplines

Atomic, Molecular and Optical Physics | Optics | Physical Sciences and Mathematics | Physics

Publication Details

Journal of Applied Physics, vol. 126, no. 2. This article may be downloaded for personal use only. Any other use requires prior permission of the author and AIP Publishing. This article appeared as Kennedy, N., Duffy, R., Mirabelli, G., Eaton, L., Petkov, N., Holmes, J. D., Hatem, C., Walsh, L. and Long, B. (2019) 'Monolayer doping of silicon-germanium alloys: A balancing act between phosphorus incorporation and strain relaxation', Journal of Applied Physics, 126 (2), 025103 (9 pp). 10.1063/1.5086356 and may be found at https://aip.scitation.org/doi/10.1063/1.5086356

Abstract

This paper presents the application of monolayer doping (MLD) to silicon-germanium (SiGe). This study was carried out for phosphorus dopants on wafers of epitaxially grown thin films of strained SiGe on silicon with varying concentrations of Ge (18%, 30%, and 60%). The challenge presented here is achieving dopant incorporation while minimizing strain relaxation. The impact of high temperature annealing on the formation of defects due to strain relaxation of these layers was qualitatively monitored by cross-sectional transmission electron microscopy and atomic force microscopy prior to choosing an anneal temperature for the MLD drive-in. Though the bulk SiGe wafers provided are stated to have 18%, 30%, and 60% Ge in the epitaxial SiGe layers, it does not necessarily mean that the surface stoichiometry is the same, and this may impact the reaction conditions. X-ray photoelectron spectroscopy (XPS) and angle-resolved XPS were carried out to compare the bulk and surface stoichiometry of SiGe to allow tailoring of the reaction conditions for chemical functionalization. Finally, dopant profiling was carried out by secondary ion mass spectrometry to determine the impurity concentrations achieved by MLD. It is evident from the results that phosphorus incorporation decreases for increasing mole fraction of Ge, when the rapid thermal annealing temperature is a fixed amount below the melting temperature of each alloy.

Recommended Citation

Kennedy, N., Duffy, R., Mirabelli, G., Eaton, L., Petkov, N., Holmes, J. D., Hatem, C., Walsh, L. and Long, B. (2019) 'Monolayer doping of silicon-germanium alloys: A balancing act between phosphorus incorporation and strain relaxation', Journal of Applied Physics, 126 (2), 025103 (9 pp). 10.1063/1.5086356