Lattice sites of ion implanted Li in diamond

Abstract

Radioactive Li ions were implanted into natural IIa diamonds at temperatures between 100 K and 900 K. Emission channelling patterns of α-particles emitted in the nuclear decay of 8 Li (t 1/2 = 838 ms) were measured and, from a comparison with calculated emission channelling and blocking effects from Monte Carlo simulations, the lattice sites taken up by the Li ions were quantitatively determined. A fraction of 40(5)% of the implanted Li ions were found to be located on tetrahedral interstitial lattice sites, and 17(5)% on substitutional sites. The fractions of implanted Li on the two lattice sites showed no change with temperature, indicating that Li diffusion does not take place within the time window of our measurements.

Theoretical models for doping diamond for semiconductor applications

“…These vary rather widely: 0.26 eV [164], 0.9 ± 0.3 eV [163] and >125 eV [162]. In comparison, the calculated diffusion barrier for Li i at 0.85 eV is more in line with the higher experimental estimates [141].…”

“…Indeed, since conduction is in the hopping regime, it seems a plausible conclusion that conduction proceeds via implantation damage rather than Li [150]. Nuclear techniques involving the radioactive decay of 8 Li [162], show that just 40% and 17% of implanted Li lie on interstitial and substitutional sites, respectively. The sizable contribution from substitutional lithium is very important: since substitutional Li (Li s ) is (at least theoretically) a deep acceptor [143], the presence of substantial concentrations of Li at this site will inevitably lead to significant levels of self-compensation.…”

An investigation into the surface termination and near-surface bulk doping of oxygen-terminated diamond with lithium at various annealing temperatures

“…One of the reasons for this is the low solubility of Li in diamond [11]. Researchers have previously attempted to incorporate Li into the diamond lattice by the processes of implantation [12,13], diffusion [14,15], and by gas phase in chemical vapor deposition (CVD) [16][17][18]. Zamir et al [19] have demonstrated the possibility of doping diamond with higher concentrations of dopants Li and N using lithium nitride suspension and gaseous ammonia, respectively.…”

Radioactive ion beams in solid state physics

“…Nuclear techniques employ the radioactive nuclei as probes of their structural or electronic lattice environment either in metals (Lindroos et al . 1992), insulators (Restle et al . 1995), semiconductors or superconductors (Correia et al .…”