Chee Yong Fong

Spin Coating Deposition of c-Oriented Wurtzite Gallium Nitride Thin Film

Spin coating growth and characterisations of c-oriented wurtzite structure gallium nitride (GaN) thin film on silicon (Si) substrate with (100) orientation was reported. The precursor solution consisted of a readily available gallium (III) nitrate hydrate powder, ethanol and diethanolamine as starting material, solvent and surfactant. All the structural and optical results showed that c-oriented wurtzite GaN thin film was deposited on Si (100) substrate. Compared with earlier reported work using sol-gel deposition, significant improvements in the structural quality of the GaN thin film were observed. The FWHM value of the thin film was approximately 2.60°. The framework described here is both an easy in setup and simple method as compared to other method such as MBE, MOCVD, and radio frequency sputtering to produce c-oriented wurtzite structure GaN thin film.

Radio-Frequency Sputtering Growth of Indium Nitride Thin Film on Flexible Substrate

The study signifies the radio-frequency (RF) sputtering growth and characterizations of indium nitride (InN) thin films deposited on flexible substrates. A three-inch diameter indium (In) sputtering target with purity of 99.999% was used. The deposition was carried out at room temperature and with substrate temperature of 200 °C. The surface morphologies, structural and optical properties of the deposited thin films were examined by using field-emission scanning electron microscopy, energy dispersive spectroscopy, X-ray diffraction as well as Fourier transform infrared spectroscopy. All the results revealed that InN thin films have been successfully deposited on the flexible substrates in the gas mixture ambient of argon and nitrogen.

Effects of Nitridation Temperatures on Gallium Nitride Thin Films Formed on Silicon Substrates

In this article, GaN thin films were successfully grown on p-type silicon (p-Si) substrates with orientation (100) through spin coating method followed by nitridation in ammonia ambient at various temperatures (750 °C, 850 °C, and 950 °C). The morphology of the GaN thin films were performed by using field-emission scanning electron microscopy. The results showed that the grain size increases with increasing nitridation temperature from 750 °C to 950 °C. Optical analysis of the GaN thin films was performed using Fourier transform infrared spectroscopy. It was confirmed from the results that the reflectance intensity of the transverse optical and longitudinal optical phonon modes of wurtzite GaN increases with increasing nitridation temperature. All the measured results show that nitridation temperature plays a very important role in improving the quality of the GaN thin films. Finally, the results revealed that the 950 °C was the optimal growth nitridation temperature for synthesizing GaN thin film.

Fabrication and characterization of macroporous zinc oxide

In this work, we report on the fabrication of porous zinc oxide (ZnO) via electrochemical etching. Single crystal bulk ZnO was electrochemically etched with the used of hydrochloric acid. The surface morphology and the optical properties of the unetched and etched samples were characterized by means of scanning electron microscopy (SEM) and photoluminescence (PL) spectroscopy. The SEM results reveal that macroporous ZnO with highly symmetry hexagonal pits were successfully obtained. Finally, the PL results show that a significant enhancement of near band edge emission was observed for the etched sample.