Phase transitions of room temperature RF-sputtered ZnO/Mg0.4Zn0.6O multilayer thin films after thermal annealing |
| |
Authors: | Jian Zhang Chen Chih-Hung LiI-Chun Cheng |
| |
Affiliation: | a Institute of Applied Mechanics, Taipei 10617, Taiwanb Institute of Photonics and Optoelectronics and Department of Electrical Engineering, National Taiwan University, Taipei 10617, Taiwan |
| |
Abstract: | We report the thermal stability of room-temperature RF-sputtered Mg0.4Zn0.6O thin films and ZnO/Mg0.4Zn0.6O superlattices at 600 °C and 800 °C. The phase of room-temperature as-sputtered Mg0.4Zn0.6O is crystalline ZnO embedded in an amorphous or short-range-ordered hexagonal MgZnO matrix. Annealing at either 600 °C or 800 °C for 5 min transforms the matrix into a crystalline hexagonal wurtzite structure, leading to a decrease of the optical bandgap (Eg) of Mg0.4Zn0.6O. This also results in a slight change near the absorption edge of the superlattice transmission spectrum. The films precipitate cubic MgZnO after heating Mg0.4Zn0.6O at 800 °C for 5 min; by contrast, precipitations take at least 3 h if the samples are heated at 600 °C. Heating at 800 °C for more than 3 h significantly reduces the film thickness and Eg, attributed to the decomposition of superlattices and diffusion of magnesium into the substrate, respectively. On the other hand, annealing the ZnO/Mg0.4Zn0.6O superlattice at 600 °C for 12 h also produces an initial slight change in the optical transmission spectra, yet the spectra remain essentially unchanged for the remainder of the annealing process. |
| |
Keywords: | Phase transition Annealing Magnesium zinc oxide Zinc oxide Multilayers Crystal microstructure X-ray diffraction |
本文献已被 ScienceDirect 等数据库收录! |
|