The Effect of Compound Composition and Strain on Vacancies in Si/SiGe Heterostructures

Abstract

In this paper we study the effect of chemical environment and elastic strains, which can arise in layered heterostructures due to the lattice parameter mismatch, on the vacancy formation energy in random Si-Ge compounds. Ab initio calculations demonstrate a number of simple trends characterizing the vacancy formation energy dependence on vacancy charge, the number of Ge atoms in its neighbourhood and on the magnitude of elastic strains. The obtained parameters of vacancy-germanium interaction indicate, in particular, a tendency for preferential vacancy accumulation in SiGe region of Si/SiGe/Si layered structures, which is confirmed here by Monte- Carlo simulation of high-temperature vacancy annealing and agrees well with recent experimental observations.

Vacancy - Assisted Redistribution of Ge in SiGe/Si Multilayer Structures Irradiated with High Energy Ions

“…Moreover, Ge diffusion is known to be mediated by vacancies. Implantation and subsequent annealing have to lead to accumulation of vacancies in the SiGe layers [1,2] and to their assistance in Ge redistribution. In [10] the correlation in vacancies and Ge atoms distribution in SiGe layer is argued.…”

“…Implantation and subsequent annealing have to lead to accumulation of vacancies in the SiGe layers [1,2] and to their assistance in Ge redistribution. In [10] the correlation in vacancies and Ge atoms distribution in SiGe layer is argued. The last issue can be the reason for Ge accumulation in local areas in SiGe layer enriched with vacancies.…”

“…The external elastic deformations and vacancy distribution are of primary importance for adequate description of evolution of heterostructure at high temperatures. Noticeable binding of vacancies to germanium atoms and vacancy segregation in Ge-rich layers during high temperature annealing have been demonstrated by the lattice kinetic Monte-Carlo simulation [1]. Accumulation of vacancies in SiGe layers and formation of the vacancy clusters have been experimentally observed after high energy implantation [2].…”

Vacancy - Assisted Redistribution of Ge in SiGe/Si Multilayer Structures Irradiated with High Energy Ions

“…The external elastic deformations and the vacancy distribution are of primary importance for adequate description of heterostructure evolution at high temperature. The noticeable binding of vacancies to germanium atoms and vacancy segregation in Ge-rich layers during high temperature annealing are demonstrated by lattice kinetic Monte-Carlo simulation [1]. This report is aimed at study the heterostructures with SiGe quantum wells after high energy ion irradiation and postradiation heat treatments Defect introduction in implanted crystals is generally described by the model based on ballistic separation of Frenkel pairs which leads to vacancy-rich area along the ion track and interstitial-rich periphery.…”