Local vibrations of thermal double donors in silicon

Abstract

The local vibrational modes ͑LVM's͒ of the oxygen chains assigned to thermal double donors ͑TDD's͒ and other related oxygen defects in silicon are studied using accurate total-energy calculations. We find that the calculated LVM frequencies as well as their isotopic shifts and charge-state dependences ͑temperature dependences͒ for the oxygen chains agree closely with the corresponding experimental quantities, which supports our assignments of the O 2i -O 2r chain to TDD1 and the O i -O nr -O i chains to TDDn (nϾ1) (O i is an interstitial oxygen and O r a threefold coordinated oxygen belonging to a ring͒.

First-principles study of migration, restructuring, and dissociation energies of oxygen complexes in silicon

“…The energies are used in a general kinetic model that will be reported in a forthcoming publication. 30 A short report of this work has appeared earlier. 24 The format of this paper is as follows.…”

Interstitial oxygen loss and the formation of thermal double donors in Si

“…13 observed in the kinetic simulations because the O 3 chain is one of the FDS in the consecutive reactions. 11,18,20 The In conclusion, we have studied the complex kinetics of dissolved oxygen in silicon. Our results show that the detailed understanding of experimental characterization can be achieved through the combination of first-principles total energy calculations and kinetic modeling.…”

“…11,18 -20 We find that the chain-like oxygen complexes are energetically most favorable and have the lowest migration energies. 11,18,20 The oxygen chains are ring-type and systematically assigned to TDDn with increasing number of oxygen atoms up to O 14 as follows: 11,20 In the kinetic model, the association of two migrating oxygen chains O j ͑containing j O atoms͒ and O k into an O jϩk complex occurs with the reaction rate (1 The restructuring of the complexes O k into the other structures occurs with the rate exp(Ϫ⌬E/kT)͓O k ͔ where is a frequency factor and ⌬E is the activation energy for the restructuring process. The longest O chains considered consist of 14 O atoms.…”

“…According to our kinetic simulations, the TDD growth is caused by the consecutive reactions where fast diffusing O 2i s and ring-type oxygen chains ͑including the TDDs͒ all capture less mobile O i s. 11,20 The calculated migration energies are 2.3 eV for O i , 0.4 -1.6 eV for O 2 -O 9 , and 1.6 -2.1 eV for O 10 -O 13 , respectively. 11,18 Each O i capture gives rise to a formation of a new TDD: TDDnϩO i →TDD(nϩ1). The main reason for this behavior is the fact that ͓O i ͔ is several orders of magnitude larger than any other ͓O k ͔, making the association terms 4 r 0 (…”

“…13,16,17 Our kinetic model-including all processes of association, dissociation, and restructuring between isomers of oxygen complexes-is described in more detail elsewhere. 18 All energies used in the kinetic model are obtained by the density-functional total energy calculations. 11,18 -20 We find that the chain-like oxygen complexes are energetically most favorable and have the lowest migration energies.…”