Excimer laser crystallization of amorphous silicon carbide produced by ion implantation

Abstract

4H-SiC was implanted with 100–250keV Ge+ and Xe+ ions and doses of 1×1014 to 1×1016cm−2 at room temperature in order to produce 40–200nm thick amorphous surface layers. The samples were irradiated with 1–50,000 pulses of a KrF excimer laser (248nm wavelength, 30ns pulse duration) using fluences of 150–900mJ/cm2 to investigate the crystallization process as a function of the laser parameters. Crystallization as well as redistribution of the impurity atoms were analyzed by Rutherford backscattering spectrometry and infrared reflection measurements. Phase transitions occurring during the irradiation were studied by means of time-resolved reflectivity measurements. In order to explain the observed phase transitions numerical analysis was performed by solving the inhomogeneous heat flow equation using the parameters of the corresponding phases. In this work, we give a consistent description of the experimental results by the numerical simulations for the given laser setup. Depending on the amorphous layer thickness, melting, solidification, and crystallization of the amorphous phase can be effectively controlled by both the laser fluence and the number of laser pulses.