TY - JOUR

T1 - Surfactant-mediated epitaxy of thin germanium films on SiGe(001) virtual substrates

AU - Schmidt, J.

AU - Tetzlaff, D.

AU - Bugiel, E.

AU - Wietler, T. F.

N1 - Publisher Copyright: © 2016 Elsevier B.V. Copyright: Copyright 2016 Elsevier B.V., All rights reserved.

PY - 2017/1/1

Y1 - 2017/1/1

N2 - We report on the impact of a surfactant on the growth mode and strain relaxation of thin Ge films on Si0.21Ge0.79 virtual substrates grown by surfactant mediated epitaxy on Si(001) wafers. Ge epitaxy without surfactant results in island formation after deposition of only 5 nm Ge. A certain part of the strain in the Ge islands is relaxed via interfacial misfit dislocations, which are located within the core part of the islands. We discuss the possibilities for the occurrence of three-dimensional growth at low Ge layer thickness. The use of Sb as a surfactant suppresses three-dimensional islanding and enables the growth of smooth pseudomorphically strained Ge films on Si0.21Ge0.79(001) virtual substrates up to a thickness of 10 nm. At thicknesses higher than 20 nm, the films relax via the formation of a misfit dislocation network at the Ge/ Si1−xGex interface. The surface roughness of up to 30 nm thick layers is below 1.6 nm. Our experimental results corroborate the calculated thickness for plastic relaxation of Ge on Si1−xGex. The effect of the surfactant on the growth of the virtual substrate and on the subsequent growth of Ge on Si0.21Ge0.79 is discussed.

AB - We report on the impact of a surfactant on the growth mode and strain relaxation of thin Ge films on Si0.21Ge0.79 virtual substrates grown by surfactant mediated epitaxy on Si(001) wafers. Ge epitaxy without surfactant results in island formation after deposition of only 5 nm Ge. A certain part of the strain in the Ge islands is relaxed via interfacial misfit dislocations, which are located within the core part of the islands. We discuss the possibilities for the occurrence of three-dimensional growth at low Ge layer thickness. The use of Sb as a surfactant suppresses three-dimensional islanding and enables the growth of smooth pseudomorphically strained Ge films on Si0.21Ge0.79(001) virtual substrates up to a thickness of 10 nm. At thicknesses higher than 20 nm, the films relax via the formation of a misfit dislocation network at the Ge/ Si1−xGex interface. The surface roughness of up to 30 nm thick layers is below 1.6 nm. Our experimental results corroborate the calculated thickness for plastic relaxation of Ge on Si1−xGex. The effect of the surfactant on the growth of the virtual substrate and on the subsequent growth of Ge on Si0.21Ge0.79 is discussed.

KW - A1. Surface morphology

KW - A3. Molecular beam epitaxy

KW - A3. Surfactant mediated epitaxy

KW - B1. Germanium silicon alloys

KW - B2. Strained Ge

KW - B2. Virtual substrates

UR - http://www.scopus.com/inward/record.url?scp=84978835215&partnerID=8YFLogxK

U2 - 10.1016/j.jcrysgro.2016.06.053

DO - 10.1016/j.jcrysgro.2016.06.053

M3 - Article

AN - SCOPUS:84978835215

VL - 457

SP - 171

EP - 176

JO - Journal of Crystal Growth

JF - Journal of Crystal Growth

SN - 0022-0248

ER -