Choong Hee Lee

Effect of rapid thermal annealing on electrical and optical properties of Ga doped ZnO thin films prepared at room temperature

Ga doped ZnO (GZO) thin films were prepared by pulsed laser deposition on glass substrate at room temperature. Structural, optical, and electrical properties of these films were analyzed in order to investigate their dependence on oxygen pressure and rapid thermal annealing (RTA) temperature. High quality GZO films with a low resistivity of 2.92×10−4Ωcm and a transparency above 94% were able to be formed at an oxygen pressure of 3×10−2Torr and a RTA temperature of 400°C. A four point probe method, x-ray diffraction, atomic force microscopy, and ultraviolet–near-infrared grating spectrometer are used to investigate the properties of GZO films.

New Crystallization Method of Amorphous Silicon by Selective Area Heating for Stamp Process

We propose a new crystallization technique called selective area heating. In this study, we investigated a new technique for high-reliability selective area crystallization of a-Si films that does not cause thermal damage to glass substrates. We reduced the crystallization time as compared to the conventional solid phase crystallization method using a stamp-type isolated thin heater. The thin heater was fabricated with a layer of Pt on a quartz substrate via Ta adhesion and capping layers. A crystalline transverse optic phonon peak at about 519 cm−1 was seen in Raman scattering spectra, showing that the films were crystallized. The poly-Si grain size was found to be smaller than 100 nm, and the dendritic structure was found using scanning electron microscopy.