Defects in Irradiated Silicon. I. Electron Spin Resonance of the Si-ACenter

Abstract

The Si -A center is a major, radiation-damage defect produced in "pulled" silicon by a room temperature irradiation. As a result of studies described in this paper (I), and the following one (II), it is concluded that this center is a lattice vacancy with an oxygen atom impurity bridging two of the four broken bonds associated with the vacancy. Spin resonance and electrical activity arise from an electron trapped in the other two bonds. In this paper (I), the spin resonance studies are described. A molecular orbital treatment of the trapped electron wave-function satisfactorily accounts for the observed g tensor, as well as the hyperfine interaction observed with neighboring 4.7% abundant Si nuclei. Study of the changes in the spectrum of a sample subjected to uniaxial stress are also described. Under stress, the amplitudes of the individual resonance components (which correspond to different orientations of the defect in the crystal) are observed to change. This results from (1) electronic redistribution of the trapped electrons among the defects, and (2) thermally activated reorientation of the defects themselves under the applied stress. These two effects are separated and a quantitative study of their magnitudes and signs, as well as their rates, is given. The results confirm many of the important microscopic features of the model.

Vacancy and interstitial depth profiles in ion-implanted silicon

“…DLTS spectrum of an n-type FZ sample implanted with 1.4 ϫ10 8 /cm 2 B ͑6.8 MeV͒ ions at an angle of incidence of 7°relative to the surface normal. The rate window is ͑200 ms͒ Ϫ1 and the filling pulse duration is 50 ms. 18 with a large capture cross section (ϳ9ϫ10 Ϫ15 cm 2 ) while the second part ( p Ͼ10 Ϫ4 s) is related to the bistable C i C s pair 19 with a small apparent capture cross section (ϳ8 ϫ10 Ϫ18 cm 2 ). The configurational-coordinate energy diagram for the acceptor state of the C i C s pair, as determined by Song et al, 19 is shown in Fig.…”

Room-temperature defect-engineered spin filter based on a non-magnetic semiconductor

“…The difference between the Ga i defects in the RTA and as-grown samples lies at their neighbouring atoms and geometric locations. By using a one-electron linear combination of atomic orbital scheme 26 and the charge density of the 4s electron ( ) 2 4 0 s ψ =72.7x10 24 cm -3 for a free neutral Ga atom 25,27 , the localization of the electron wave functions at the Ga i 2+ defects is estimated to be 20% (as-grown) and 16% (RTA). The rather strong localization shows that they are deep-level defects, a prerequisite for efficient carrier recombination.…”

Radiation-produced defects in germanium: experimental data and models of defects

“…First of all, considerable interest is attracted to trapping of mobile vacancies at oxygen atoms resulting in formation of oxygen-vacancy pairs, the so-called A-centers as in the nomenclature of defects in irradiated Si [2,23]. These defects have been extensively studied by Hall effect measurements and DLTS spectroscopy; see for instance [24][25][26] and the literature contained therein.…”