Passivation of the grain boundary electrical activity in multicrystalline silicon: aluminum treatment efficiency

The electrical activity of grain boundaries in multicrystalline silicon has been investigated using electron beam induced current (EBIC) contrast imag ing and potential barrier height and interface state density calculation fr om IV and C-V measurements. It is shown that 1 mu m evaporated aluminum lay er deposited on the back surface of a silicon sample, followed by annealing at 850 degrees C for 30 min, reduces the electrical activity of grain boun daries: the interface states density and the EBIC contrast associated with the recombination at grain boundaries decrease. It is also established that the efficiency of aluminum passivation depends on the cooling rate after t he diffusion of aluminum at 850 degrees C. The gettering mechanism is discu ssed. (C) 1999 Elsevier Science Ltd. All rights reserved.