ALPHA-EMISSION CHANNELING INVESTIGATIONS OF THE LATTICE LOCATION OF LI IN GE

The alpha-emission channeling and blocking technique is a direct metho d for lattice site determination of radioactive atoms in single crysta ls. Position-sensitive detection of emitted alpha-particles provides a n efficient means of carrying out such experiments at very low doses ( 10(10)-10(11) cm(-2) implanted probe atoms per spectrum), Comparison o f the experimental data with Monte Carlo simulations of complete two-d imensional channeling patterns (e,g. +/-2 degrees around [100], [110] and [211] axes, which also includes all relevant planar directions) al lows for straightforward identification and quantitative determination of occupied lattice sites, while at the same time the energy spectrum of emitted alpha-particles gives information on the probe atom depth distribution. We illustrate this for the case of ion implanted Li-8 (t (1/2) - 0.8 s) in Ge, where we identify mainly tetrahedral Li at room temperature, and bond-centered Li at slightly elevated temperature.