Laser Quenching of Amorphous Si from the Melt Containing Dopants

Abstract

ABSTRACTThe formation of amorphous Si by the quench of a thin surface layer melted by fast UV laser irradiation has been investigated. The starting (111) surface layers were either pure or doped with As, Bi, In and Te by implantation. The asimplanted samples were recrystallized by ruby laser irradiation resulting in surface accumulation of Bi,In and Te. For the same UV irradiation condition, the amorphous layer formed in As, Bi, In or Te doped Si is about twice the thickness of the amorphous layer formed on pure Si. In the presence of the surface accumulation of Bi, In or Te, the amorphization results in an inward segregation of the dopant. For In, a very thin metal layer ˜15Å thick, is formed 150Å beneath the amorphous surface. These results show that the amorphous-liquid interfacial segregation coefficients for Bi, In or Te are less than unity and that the amorphous solidification proceeds from the surface and bottom of the liquid layer.