Phosphorus doping into 4H-SiC by irradiation of excimer laser in phosphoric solution

We developed a method to dope phosphorus into 4H-SiC by irradiating excimer laser light to 4H-SiC immersed in phosphoric acid solution. A KrF excimer laser was used. The surface is slightly ablated by the laser irradiation. However, no amorphous layer is generated near the surface. Phosphorous is introduced at a concentration of over 1020 cm-3 near the crystal surface. The laser irradiation in phosphoric acid solution significantly improves the ohmic contact characteristic between metal and 4H-SiC. Hall effect measurement shows that the irradiation produces an n-type layer at the surface whose sheet carrier concentration is 2:25-1012 cm-2. In addition, we produce a pn junction by irradiating p-type 4H-SiC. The pn junction shows a rectifying characteristic whose on/off ratio is over 8 decades and ideality factor is 1.06.