Electronic Structure of Strained Crystals

Under strain, the propeties of electron inside crystal drastically change. We investigate the electronic structures and the other properties of crystal under two types of strain.

This project is in collaboration with

Prof. Takeshi Inaoka at Univ. Ryukyus,

Prof. Toshio Takahashi at Tokyo Gakugei Univ.

Assist. Prof. Tetsuro Shirasawa at ISSP, Univ. Tokyo

Funding:

STARC FY2008-FY2010 (SNTakeda)

Grant-in-Aid for Scientific Research FY2010-FY2013 (Prof. Inaoka, SNTakeda)

Grant-in-Aid for Scientific Research FY2012-FY2014(SNTakeda, Prof. Takahashi, Prof. Shirasawa)

1. bi-axially tensile strain

Bi-axially tensile strain in Si is realized by using Si_1-x Ge_x layer as a substrate.The Si layer grown on Si_1-x Ge_x has a lattice constant same as Si_1-x Ge_x. The lattice constant of Si_1-x Ge_x can vary depending on the Ge concentration x. The maximum strain is about 1 %.

2. Uni-axial tensile strain

This is archieved by pusing the crystal from the backside.We developed a maniplulator which can apply uni-axial tensile strain to samples.You can see the distortion of Silicon wafer in the movie below.

3. Amount of Strain

We have developed UHV-Raman spectroscopy to measure the amount of the stain.