Evolution of vacancy-related defects upon annealing of ion-implanted germanium

Abstract

Positron annihilation spectroscopy was used to study defects created during the ion implantation and annealing of Ge. Ge and Si ions with energies from 600 keV to 2 MeV were implanted at fluences between 1 ϫ 10 12 cm −2 and 4 ϫ 10 14 cm −2 . Ion channeling measurements on as-implanted samples show considerable lattice damage at a fluence of 1 ϫ 10 13 cm −2 and a fluence of 1 ϫ 10 14 cm −2 was enough to amorphize the samples. Positron experiments reveal that the average free volume in as-irradiated samples is of divacancy size. Larger vacancy clusters are formed during regrowth of the damaged layers when the samples are annealed in the temperature range 200-400°C. Evolution of the vacancy-related defects upon annealing depends noticeably on fluence of ion implantation and for the highest fluences also on ion species.

Defect identification in semiconductors with positron annihilation: Experiment and theory

“…Vacancies have also been found to pair with donors in Ge with positron annihilation (Arutyunov and Emtsev, 2007), while thorough investigations are still to be performed. Even though germanium exhibits interesting properties in ion implantation, i.e., it is easily amorphized and the recrystallization temperature is low (Hickey et al, 2007), surprisingly few positron studies seem to have been performed (Krause-Rehberg et al, 1993;Slotte et al, 2008). The situation is completely different for the Si-Ge alloys which have been studied to a large extent.…”

“…Monovacancies and divacancies have been identified (Corbel, Moser, and Stucky, 1985;Polity and Rudolf, 1999;Kuitunen et al, 2008;Slotte et al, 2008Slotte et al, , 2011 and their stability at and below room temperature investigated. Vacancies have also been found to pair with donors in Ge with positron annihilation (Arutyunov and Emtsev, 2007), while thorough investigations are still to be performed.…”

Calculation of positron annihilation characteristics of six main defects in6H-SiC and the possibility to distinguish them experimentally

“…The measurement of the positron lifetime before annihilation, or of the Doppler broadening of the annihilation line, gives information about the annihilation environment (open-volume size and nature of the atoms surrounding the vacancy) [10]. Sensitive at a concentration level as low as 10 15 cm −3 , these methods have commonly and successfully been used since the mid-1990s to study defects in semiconductors such as Si, Ge, or GaN [11][12][13][14][15].…”

Electrical compensation via vacancy–donor complexes in arsenic-implanted and laser-annealed germanium

“…Thus, the trap-related parameters point toward V 2 -or V 3 -sized defects, ruling out larger V clusters. 23 The differences in the turning point between the four samples appear relatively small, which implies that the trapping defects could be of the same kind in all of the samples. Saturation trapping of positrons also explains why the data are similar for different As contents.…”