Aluminum doping of 4H-SiC by irradiation of excimer laser in aluminum chloride solution

We have found that aluminum doping into 4H-SiC is performed by irradiating excimer laser light to 4H-SiC immersed in aluminum chloride solution. Aluminum is introduced in SiC at the concentration of over 1 × 10 ²⁰cm^-3 near the surface while, chlorine hardly diffuses into 4H-SiC. After the laser irradiation in aluminum chloride solution, the resistance of the laser-irradiated region decreases with increasing laser fluence. Hall effect measurement shows that the laser irradiation produces a p-type layer and that its sheet carrier concentration is 2.14 × 10 ¹¹cm^-2. In addition, we produce a pn junction by doping the surface of n-type 4H-SiC and by aluminum doping. The pn junction shows rectifying characteristics whose on/off ratio is about 7 decades and ideality factor is 1.15. This technique is one of the strong candidate local doping techniques for SiC.