On the homogeneous depth temperature distribution realized at the pulsed laser annealing

As usual, pulsed laser annealing (LA) of semiconductors is connected with a depth temperature gradient caused by the decay of radiation in the direction of its propagation. The situation of two square pulses simultaneously supplied on the sample from two opposite sides is considered where the pulse duration tau1 is much less than tau2 and energy E1 is much less than E2 according to the first and second pulse. One dimensional approximation is used and heat exchange with the environment is neglected. Wave lengths lambda1 and lambda2 must correspond to strong and weak absorption of radiation by the cold sample and E1 must be enough for melting of thin surface layer (in comparison with the depth of annealing layer delta). For semiconductor-to-metal type of melting, the motion of interface deep into the sample near melting temperature is realized in laser annealing process. Expressions for the temperature profile in installed regime of motion are obtained. Estimations for c-Si showed that LA in nanosecond range can be realized at the depth of few microns. (author)