High level active n+ doping of strained germanium through co-implantation and nanosecond pulsed laser melting
Abstract
Obtaining high level active n+ carrier concentrations in germanium (Ge) has been a significant challenge for further development of Ge devices. By ion implanting phosphorus (P) and fluorine (F) into Ge and restoring crystallinity using Nd:YAG nanosecond pulsed laser melting (PLM), we demonstrate 1020 cm−3 n+ carrier concentration in tensile-strained epitaxial germanium-on-silicon. Scanning electron microscopy shows that after laser treatment, samples implanted with P have an ablated surface, whereas P + F co-implanted samples have good crystallinity and a smooth surface topography. We characterize P and F concentration depth profiles using secondary ion mass spectrometry and spreading resistance profiling. The peak carrier concentration, 1020 cm−3 at 80 nm below the surface, coincides with the peak F concentration, illustrating the key role of F in increasing donor activation. Cross-sectional transmission electron microscopy of the co-implanted sample shows that the Ge epilayer region damaged during implantation is a single crystal after PLM. High-resolution X-ray diffraction and Raman spectroscopy measurements both indicate that the as-grown epitaxial layer strain is preserved after PLM. These results demonstrate that co-implantation and PLM can achieve the combination of n+ carrier concentration and strain in Ge epilayers necessary for next-generation, high-performance Ge-on-Si devices.
Document Details
- Document Type
- Pub Defense Publication
- Publication Date
- Apr 23, 2018
- Source ID
- 10.1063/1.5012512
Entities
People
- Anu Agarwal
- Austin J. Akey
- Corentin Monmeyran
- David Pastor
- E. Napolitani
- Eric Mazur
- Hemi H. Gandhi
- Iain F Crowe
- Jürgen Michel
- L. C. Kimerling
- Michael J Aziz
- Ruggero Milazzo
- Russell Gwilliam
- Yan Cai
Organizations
- Complutense University of Madrid
- Defense Threat Reduction Agency
- Harvard University
- Massachusetts Institute of Technology
- United States Air Force
- United States Department of Defense
- University of Manchester
- University of Padua
- University of Surrey