LATTICE SITES OF ION-IMPLANTED LI IN INDIUM-ANTIMONIDE

We have studied the interaction of Li and implantation defects using t he emission channeling technique after implantation of 60 keV Li-8 ion s into n- and p-InSb. Emission channeling patterns of alpha-particles emitted in the nuclear decay of Li-8(t1/2 = 838 ms) were measured for temperatures between 50 and 600 K. A quantitative determination of Li site fractions was achieved by comparing the experimentally observed c hanneling and blocking patterns to calculated emission channeling effe cts from Monte Carlo simulations. Below 130 K about 60% of the Li atom s occupy tetrahedral interstitial sites. Between 130 and 200 K a site change to substitutional sites is observed for p-InSb as well as n-InS b, resulting in substitutional fractions of Li of about 60-70%. Substi tutional Li is stable up to about 425 K in p-InSb and 475 K in n-InSb. From these temperatures we have estimated dissociation energies of 1. 1 and 1.2 eV, respectively. For higher temperatures out-diffusion of L i to the surface is observed. The behavior of Li in InSb was found to be similar to the other III-V semiconductors GaAs, GaP and InP. Whethe r diffusion of Li or the mobilization of vacancy defects is the domina nt process responsible for the observed lattice site changes is discus sed.