Interstitial boron in silicon: A negative-Usystem

First-principles calculations of interstitial boron in silicon

“…However, electron irradiation at cryogenic temperatures has been found to displace substitutional B atoms into an interstitial configuration. [1][2][3] In these studies this defect was also found to have negative-U properties, i.e., it is able to trap two electrons with the property that the second electron is more strongly bound than the first one. Tarnow 4 studied the charge state configurations of this defect with ab initio total-energy calculations.…”

Electron and Proton Irradiation of Silicon

“…Once the first electron is trapped at the donor level located at 0.13 eV below the conduction band, trapping of a second electron immediately follows on a deeper acceptor level located at 0.35 eV below the conduction band. This peculiar behavior is due to a large lattice relaxation following the capture of the first carrier (Harris et al, 1982(Harris et al, , 1987Troxell and Watkins, 1980). In a normal positive-U distribution, the acceptor state B i 0=À should be above the donor state B i + =0 .…”

“…Harris et al (1982) could observe the unstable neutral state by combining infrared light and low temperatures to control charge population. At high temperatures, in p-type (Watkins, 1975b(Watkins, , 1991); (B) shows the inverted distribution of its two coupled states following the negative-U character (Harris et al, 1982(Harris et al, , 1987Troxell and Watkins, 1980). Copyright Wiley-VCH Verlag GmbH&Co. KGaA.…”

Electron Paramagnetic Resonance of Material Properties and Processes

“…More recently, DLTS measurements have indicated a level at Ec-.45 eV which is identified as the B interstitial acceptor level [27]. Also, the donor level for the B interstitial has now been detected at ~ Ec -0.12 eV by DLTS measurements [29] •..…”

“…7 and 8. The important feature of these models is that migrational jumps may occur as Bi 0 decays to either Bi-or Bi+• In fact, DLTS measurements indicate that the annealing rate of the boron interstitial is considerably enhanced under minority carrier .injection in either n-or p-type silicon [27]~ Furthermore, the quadra-: tic dependence on injected current suggests a two step process: the capture of two electrons (holes) in p-type (n-type) material. Consequently, the enhanced migration of the B interstitial involves the alternation bet~en charge states which differ by two electronic charges [27].…”