Theoretical calculation of the dislocation width and Peierls barrier and stress forsemiconductor silicon**The work is supported by the National Natural Science Foundation of China (GrantNo. 10774196) and Chongqing University Postgraduates’ Science and Innovation Fund(Grant No. 200904A1A0010315).

Abstract

The dislocation width and Peierls barrier and stress have been calculated by the improvedPeierls–Nabarro (PN) theory for silicon. In order to investigate the discreteness correctionof a complex lattice quantitatively, a simple dynamics model has been used in whichinteraction attributed to a variation of bond length and angle has been considered. Theresults show that the dislocation core and mobility will be corrected significantlyby the discrete effect. Another improvement is considering the contribution ofstrain energy in evaluating the dislocation energy. When a dislocation moves, bothstrain and misfit energies change periodically. Their amplitudes are of the sameorder, but phases are opposite. Because of the opposite phases, the misfit andstrain energies cancel each other and the resulting Peierls barrier is much smallerthan that given by the misfit energy conventionally. Due to competition betweenthe misfit and strain energies, a metastable state appears separately for glide90° and shuffle screw dislocations. In addition, from the total energy calculation it is found thatbesides the width of dislocation, the core of a free stable dislocation may be differentaccording to where the core center is located. The exact position of the core center can bedirectly verified by numerical simulation, and provides a new prediction that can be used toverify the validity of PN theory. It is interesting that after considering discretecorrection the Peierls stress for glide dislocation coincides with the critical stressat low temperature, and the Peierls stress for shuffle dislocation coincides withthe critical stress at high temperature. The physical implication of the results isdiscussed.