Vacancy generation resulting from electrical deactivation of arsenic

Abstract

Electrical deactivation of arsenic in highly doped silicon has been studied using the positron-beam technique. Direct experimental evidence linking the formation of arsenic-vacancy complexes (i.e., Asn-v) to the deactivation process is reported. The average number of arsenic atoms per complex, n̄≳2, was determined by comparing the observed complex concentrations with those of the deactivated arsenic inferred from Hall-effect measurements.

Identification of Vacancy-Impurity Complexes in Highlyn-Type Si

“…The core electron momentum distribution can be used to identify the atoms surrounding the vacancy [6]. In earlier measurements in heavily Asor Sb-doped Si, vacancy defects have been detected and the momentum distribution induced by the dopant atom surrounding the vacancy has been qualitatively observed [7][8][9]. However, these experiments do not reveal the open volume of the vacancies, the number of dopant atoms in their surroundings, or their concentrations.…”

Diffusion ofn-type dopants in germanium

“…Finally, it should be stressed that in Si, previous experimental and theoretical studies attributed to As n V clusters the electrical deactivation of free carriers in heavily As-doped Si. [106][107][108][109][110] This is an interesting similarity between the two materials, especially when considering that in Si both V and I impact the defect processes, whereas in Ge vacancies dominate.…”

Defect identification in semiconductors with positron annihilation: Experiment and theory

“…Many computational first-principles studies have addressed the electrical properties of these defects as well as their energetics including diffusion barriers [see, e.g., Pandey et al (1988), Ramamoorthy and Pantelides (1996), Xie and Chen (1999), Christoph Mueller, Alonso, and Fichtner (2003), and Vollenweider, Sahli, and Fichtner (2010)]. Vacancy-impurity complexes were observed quite early in positron annihilation experiments (Lawther et al, 1995) but their exact structure remained unknown. Coincidence Doppler broadening experiments combined with theoretical calculations provided the optimal method for identification of these defects.…”

“…In the irradiated samples, the experiments reveal vacancies with positron lifetimes of 250 ps (Cz-grown Si:As) and 300 ps (undoped FZ-grown Si), corresponding to monovacancy-sized defects and divacancies, respectively (Kauppinen et al, 1998;Saarinen et al, 1999). Isolated monovacancies are very mobile in Si already at room temperature (Watkins, 1986), and hence in undoped FZ-grown Si the vacancy defects that survive after irradiation are divacancies formed through the migration process, while in As-doped Cz-grown Si the mobile monovacancies find As atoms and form stable vacancy-donor complexes (Lawther et al, 1995;Saarinen et al, 1999). Positron lifetime spectra in Cz-grown Si doped with As (10 19 cm À3 ) or P (10 20 cm À3 ) also have a single component of about 220 ps corresponding the bulk lifetime B in Si.…”