Zone-melting germanium film crystallization with tungsten encapsulation

Zone-melting crystallization of Ge film by using an rf zone-heating slider system is described. A buffer layer of tungsten between the germanium and the amorphous substrate was found to prevent molten germanium agglomeration. In addition to the buffer layer, the use of a tungsten capping layer was found to promote large area and flat surface growth. Crystallized material included a single crystal region ∼100 μm wide width and several millimeters long approximately along the zone-melt sliding direction. Also, single crystalline islands patterned into 80×140 μm rectangles were prepared. Auger electron analysis showed neither tungsten autodoping in crystallized germanium nor enhanced diffusion along grain and twin boundaries.