Athermal annealing of silicon

摘要

We experimentally demonstrate the annealing an electrical activation of doped silicon without the direct application of heat as in conventional thermal annealing or pulsed laser annealing. 25x25x3 mm samples of silicon doped by neutron transmutation were irradiated with a short pulse from a 1.06-micron laser. The few joule laser pulse was focused to mmdiameter surface spot which resulted in high power (approx 10~911) W/cm~2) capable of launching shocks into the entire sample. In a few instances the entire silicon slab, including regions far outside the illuminated spot, was annealed and electrically activated. In the annealed samples electrical activation of donors throughout the slab, measured with a four-point probe, was uniform and comparable to that of thermally annealed control samples. Far-infrared spectroscopy and Hall measurements also showed that the donor species was activated and Raman spectroscopy demonstrated marked improvement in the crystal structure. We conjecture that the annealing was caused by the mechanical energy that was launched into the slab by the laser pulse. Results of experiments on an ion-implanted silicon sample are also discussed.