In-situ observation of rapid crystalline growth induced by excimer laser irradiation to Ge/Si stacked structure

Excimer laser induced melting and solidification of Ge films on Si have been investigated using in-situ measurement of transient conductance of the films. 35-nm-thick Ge films are partially melted by irradiating them with laser energies higher than 114 mJ/cm2 and are completely melted at 191 mJ/cm2. The crystalline growth of Ge irradiated with laser energies lower than 191 mJ/cm2 proceeds independently of the underlying Si film, however, by irradiating at a higher energy, the diffusion of Si atoms into molten Ge and the formation of SixGe1−x layer result. The electrical conductivity of the SixGe1−x film decreases with Si composition until x = 0.16, and then increases and peaks at around x = 0.25 to 0.3, presumably due to defected and/or strained bonds in the film induced by underlying Si layer.