A positron annihilation spectroscopy study of porous silicon

Positronics and nanotechnologies: Possibilities of studying nano-objects in technically important materials and nanomaterials

“…For the experimental value (u 1/2 ) g2 ¼ 0.8 mrad the calculated radius was R g2 % 19.09 A % 2 nm. Consideration of the kinetics of the annihilation and transformations of p À Ps in a pore layer enables the dependence between the capture constant k tr and component intensity I g2 [24] to be written as…”

“…The capture constant of the p À Ps can be estimated using the data in Table 1 and equation (4) to be k tr % 1.2 · 10 8 s À1 . The value of the capture speed k tr can in turn be defined on the basis of the following expression [24] …”

“…1 and Table 1 of references [17] and [25] was obtained using p À Ps in porous silicon (see, for example, the sample of porous silicon PR86 (Table 1) and also Fig. 2 of references [17] and [24]). The experimental ADAP spectra of porous silicon can be closely approximated by a parabola (I p ) and by two gaussian components (I g1 , I g2 ).…”

“…The experimental ADAP spectra of porous silicon can be closely approximated by a parabola (I p ) and by two gaussian components (I g1 , I g2 ). For defect free samples of silicon [17] and also in a number of porous samples [24] these spectra are represented by the superposition of a parabola and gauss function. The radius R g2 of pores with a width (u 1/2 ) g2 can be calculated using equation (2).…”