Formation of Ge pn-junction diode by phosphorus doping with liquid immersion laser irradiation

The authors have investigated phosphorus (P) doping in Ge using immersion laser irradiation in phosphoric acid solution at room temperature (RT). The ultraviolet-laser has the penetration length under 10 nm in Ge, which indicate that the laser energy is absorbed at a few nanometers on Ge surface, thus the heating whole of substrate would be avoided with a proper condition. Besides, the liquid immersion is expected that the laser-induced heat is effectively dissipated from the surface of substrate because of higher thermal conductivity of liquid than gas.