We developed a new UV-Raman spectroscopy system for local and global strain measurements in Si. Using a 364 nm excitation laser, strain in an ultra-thin Si film can be measured. Because of the resonance effect using this particular wave length, reasonably short measurement time is realized to obtain strain mapping with keeping the sample at sufficiently low temperature. An in situ wavenumber calibration system has been newly developed for superior wavenumber resolution and precision of approximately 0.1 cm À1 . A quasi-line shape excitation light source has also been developed to verify the effective spatial resolution. Strain mapping and spectral measurements for relaxation by rapid thermal annealing in strained-Si substrates are demonstrated.

We demonstrate excitation of transverse-optical (TO) phonons in a strained-Si on insulator (SSOI) by using a high-numerical-aperture oil-immersion lens. Using this technique, the TO phonons are excited, even under the (001) Si backscattering configuration. The wave numbers of the TO phonons in SSOI thus excited are different from that of the longitudinal-optical (LO) phonon. This result indicates the coefficients of Raman wave number shift and biaxial stress are different in the LO- and TO-phonon modes. The excitation of the TO phonons allows us to study stress tensors in Si.

Phonon deformation potentials (PDPs) in Si1-xGex were investigated by oil-immersion Raman spectroscopy. Transverse optical (TO) and longitudinal optical (LO) phonon modes were separately excited for strained Si1-xGex as well as strained Si. PDPs p and q were derived with the use of the Raman wavenumber shifts of TO and LO. The obtained PDPs for Si, SiGe0.153, and SiGe0.297 were compared with one another. Furthermore, the strain-shift coefficient was also obtained and compared with the previously reported values. The p and q values allow us to precisely evaluate anisotropic biaxial stress states in Si and Si1-xGex by oil-immersion Raman spectroscopy.

Transconductance (gm) enhancement in n-type and p-type nanowire field-effect-transistors (nwFETs) is demonstrated by introducing controlled tensile strain into channel regions by pattern dependent oxidation (PADOX). Values of gm are enhanced relative to control devices by a factor of 1.5 in p-nwFETs and 3.0 in n-nwFETs. Strain distributions calculated by a three-dimensional molecular dynamics simulation reveal predominantly horizontal tensile stress in the nwFET channels. The Raman lines in the strain controlled devices display an increase in the full width at half maximum and a shift to lower wavenumber, confirming that gm enhancement is due to tensile stress introduced by the PADOX approach.