Seminar on Mathematics for various disciplines

Seminar information archive ~02/25Next seminarFuture seminars 02/26~

Date, time & place Tuesday 10:30 - 11:30 056Room #056 (Graduate School of Math. Sci. Bldg.)

2006/11/29

10:30-11:30   Room #056 (Graduate School of Math. Sci. Bldg.)
塚本 史郎 (東京大学生産技術研究所)
Atomistic view of InAs quantum dot self-assembly from inside the growth chamber
[ Abstract ]
A 'quantum dot' is a tiny region of a solid, typically just nanometres in each direction, in which electrons can be confined. Semiconductor quantum dots are the focus of intense research geared towards exploiting this property for electronic devices. The most economical method of producing quantum dots is by self-assembly, where billions of dots can be grown simultaneously. The precise mechanism of self-assembly is not understood and is hampering efforts to control the characteristics of the dots. We have used a unique microscope to directly image semiconductor quantum dots as they are growing, which is a unique scanning tunnelling microscope placed within the molecular beam epitaxy growth chamber. The images elucidate the mechanism of InAs quantum dot nucleation on GaAs(001) substrate, demonstrating directly that not all deposited In is initially incorporated into the lattice, hence providing a large supply of material to rapidly form quantum dots via islands containing tens of atoms. kinetic Monte Carlo simulations based on first-principles calculations show that alloy fluctuations in the InGaAs wetting layer prior to are crucial in determining nucleation sites.
[ Reference URL ]
http://coe.math.sci.hokudai.ac.jp/sympo/various/index.html