Increasing Laser-Doping Depth of Al in 4H-SiC by Using Expanded-Pulse Excimer Laser

Abstract

Al doping into 4H-SiC performed by irradiating pulse-width-expanded excimer laser to an Al film deposited on the 4H-SiC surface is investigated. An optical pulse stretcher was constructed to produce the laser pulse whose peak intensity was reduced as half as that of the original pulse and pulse width was expanded from 55 ns to 100 ns. The irradiation of the expanded pulses is found to reduce the ablation of the materials from the surface and enable irradiation of multiple shots. As the result, doping depth of Al is significantly increased. The multiple shots of the expanded pulses is also fund to decrease the sensitivity to spatial non-uniformity of laser intensity and increase the uniformity of doped region.