Tuning the Si(100) surface by Pb to yield high-Curie-temperature Si_1−xMn_x with MBE: A first-principles study

¹ School of Material Science and Engineering, Hainan University - Hainan 570228, PRC
² School of Physics, Nankai University - Tianjin 300071, PRC

^(a) lxzhang@nankai.edu.cn

Received: 13 August 2017
Accepted: 12 January 2018

Abstract

A high solubility and site preference for Mn doping in Si are the two keys for realizing high-Curie-temperature ferromagnetism in Si_1−xMn_x. First-principles calculations reveal that both the substitutional and interstitial Mn are more favored on the Si surface than in bulk, and the substitutional Mn is more favored than the interstitial one on the reconstructed clean Si(100) surface. However, during molecular beam epitaxy, the surface is prone to further reconstructions due to the continuous deposition of feeding species. Neither substitutional nor interstitial Mn is favored, similar to that in Si bulk. Deposition of submonolayer of Pb onto the surface can restore the electronic structure of the clean surface and the favorability of the substitutional Mn, enhancing the Mn incorporation into Si significantly.