Molecular-beam epitaxial growth of tensile-strained and n-doped Ge/Si(001) films using a GaP decomposition source

T. K.P. Luong, A. Ghrib, M. T. Dau, M. A. Zrir, M. Stoffel, V. Le Thanh, R. Daineche, T. G. Le, V. Heresanu, O. Abbes, M. Petit, M. El Kurdi, P. Boucaud, H. Rinnert, J. Murota

Research output: Contribution to journalArticlepeer-review

18 Citations (Scopus)


We have combined numerous characterization techniques to investigate the growth of tensile-strained and n-doped Ge films on Si(001) substrates by means of solid-source molecular-beam epitaxy. The Ge growth was carried out using a two-step growth method: a low-temperature growth to produce strain relaxed and smooth buffer layers, followed by a high-temperature growth to get high crystalline quality Ge layers. It is shown that the Ge/Si Stranski-Krastanov growth mode can be completely suppressed when the growth is performed at substrate temperatures ranging between 260 °C and 300 °C. X-ray diffraction measurements indicate that the Ge films grown at temperatures of 700-770 °C are tensile-strained with typical values lying in the range of 0.22-0.24%. Cyclic annealing allows further increase in the tensile strain up to 0.30%, which represents the highest value ever reported in the Ge/Si system. n-Doping of Ge was carried out using a GaP decomposition source. It is shown that heavy n-doping levels are obtained at low substrate temperatures (210-250 °C). For a GaP source temperature of 725 °C and a substrate temperature of 210 °C, a phosphorus concentration of about 1019 cm - 3 can be obtained. Photoluminescence measurements reveal an intensity enhancement of about 16 times of the direct band gap emission and display a redshift of 25 meV that can be attributed to band gap narrowing due to a high n-doping level. Finally, we discuss about growth strategies allowing optimizing the Ge growth/doping process for optoelectronic applications.

Original languageEnglish
Pages (from-to)70-75
Number of pages6
JournalThin Solid Films
Publication statusPublished - 2014 Apr 30
Externally publishedYes


  • MBE growth
  • Optoelectronics
  • Tensile strain Ge
  • n-Doping

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Surfaces and Interfaces
  • Surfaces, Coatings and Films
  • Metals and Alloys
  • Materials Chemistry


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