The crystallographic texture of thin film semiconductors is crucial to their performance in devices such as flat panel displays or thin film transistors. Laser processing is often used to irradiate the film, where melting and subsequent solidification results in grain generation. To ensure uniformity, traditional methods irradiate each surface multiple times, which forms uniformly sized grains, but in random orientations which can result in decreased mobility of charge carriers in the film. This technology is a laser processing method for generating elongated grains with prescribed orientations in thin film semiconductors. Orientating the elongated grains in favorable directions improves the performance of the thin films.
During laser processing, the crystallization of irradiated regions will match the orientation along the boundary, thus an initial texture is required. This technology allows for multiple methods of accomplishing this: zone melt recrystallization, chemical vapor deposition, sputtering, or using pulsed lasers, among many others. Once an initial texture is achieved, sequential lateral solidification (SLS) is performed to induce elongated crystal growth in the preferred orientation. A single SLS pass across the surface provides for the desired crystallographic texture, thus simplifying processing requirements.
The uniformity in orientation of experimentally produced grains was confirmed using electron microscopy techniques.
Patent Issued (US 8734584)
Tech Ventures Reference: IR M05-003