Strain-induced modulation of band structure of silicon

Abstract

This work presents ab initio study of strain-induced modulation of band structure of Si.It is shown that at straining pressures >12 GPa band structure of Si can be turned from indirect to direct. Both the bottommost conduction band and topmost valence band are located at the Γ point. The conduction band minimum at the Γ point of the strained Si is found to be much more dispersive than that at the X point of the unstressed Si.Consequently, electrical conductivity through the Γ valley is suggested to be more superior than the X point of the unstressed Si. Barrier height, which is needed to transfer electrons in the Γ point to X/L points or from X/L to Γ point have been calculated. The results have been applied to explain peculiarities of electronic structure and light emission of Si based materials containing dislocations and voids.

Electronic and Optical Properties of Dislocations in Silicon

“…As a result, the band gap energies of the indirect and direct transitions are equal for such high tensile strain and Si changes from the indirect into a direct semiconductor [80]. This conclusion is in agreement with previously reported data [85,86]. Furthermore, the shift of the conduction band minimum at the L point results in an additional indirect transition in the presence of high tensile strain.…”

“…The calculated hole mass mh = 0.285 is almost constant if strain is varied between −0.1 ≤ ε ≤ +0.1 and corresponds to previously published data [86]. The effective in-plane electron mass parallel to the strain direction (meff) decreases continuously with increasing tensile strain and is mt = 0.15m0 at ε = +0.1.…”

“…The effect of different types of strain (uniaxial, biaxial, tensile, and compressive) on the band structure of Si and device properties has been analyzed using different simulation techniques [81][82][83][84][85][86].…”

On the electronic properties of a single dislocation

“…It is generally known that strain modifies the band structure of silicon and carrier mobility by (i) the reduction of the carrier effective mass and (ii) by reduction of the intervalley phonon scattering rates. [26][27][28] For p-type material analyzed here, the potential barrier induced by the tensile strain generates the confinement of electrons along the dislocation line. 29 This is combined with changes of the electron effective masses and a reduction of the electron scattering due to conduction valley splitting, which lowers the rate of intervalley phonon scattering.…”

A study of electrical properties of dislocation engineered Si processed by ultrasound

“…As noted in Ref. [25], strain field around dislocations can modulate band structure of Si. So, one the one hand the experimental observation can be the result of the UST-induced transformation of the dislocations, which has lead to changing of their recombination properties.…”