Implantation and activation of high concentrations of boron in germanium

Yong Seok Suh, Malcolm S. Carroll, Roland A. Levy, Gabriele Bisognin, D. De Salvador, M. Alper Sahiner, Clifford A. King

Research output: Contribution to journalArticlepeer-review

28 Scopus citations

Abstract

There is renewed interest in the development of Ge-based devices. Implantation and dopant activation are critical process steps for future Ge devices fabrication. Boron is a common p-type dopant, which remarkably is active immediately after implantation in Ge at low doses. This paper examines the effect of increasing dose (i.e., 5 × 1013 - 5 × 1016 cm-2) and subsequent annealing (400 °C-800 °C for 3 h in nitrogen) on activation and diffusion of boron in Ge. Secondary ion mass spectrometry (SIMS), spreading resistance profiling (SRP), high resolution X-ray diffraction (HRXRD), Rutherford backscattering spectrometry (RBS), and nuclear reaction analysis (NRA) are used to characterize the implants before and after annealing. It is found that very high fractions of the boron dose (∼5%-55%) can be incorporated substitutionally immediately after implantation leading to very high hole concentrations, ≥ 2 × 1020 cm-3, deduced from SRP. Small increases in activation after annealing are observed, however, 100% activation is not indicated by either SRP or NRA. Negligible diffusion after annealing at either 400 °C or 600 °C for 3 h was, furthermore, observed.

Original languageEnglish (US)
Pages (from-to)2416-2421
Number of pages6
JournalIEEE Transactions on Electron Devices
Volume52
Issue number11
DOIs
StatePublished - Nov 2005

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Electrical and Electronic Engineering

Keywords

  • Annealing
  • Boron
  • Germanium
  • Ion implantation

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