Effects of thermal annealing on the microstructural properties of the lower region in ZnO thin films grown on n-Si (001)
- PDF / 420,377 Bytes
- 5 Pages / 585 x 783 pts Page_size
- 83 Downloads / 140 Views
T.W. Kima) Division of Electronics and Computer Engineering, Hanyang University, Seoul 133-791, Korea
D.I. Son Department of Information Display Engineering, Hanyang University, Seoul 133-791, Korea
W.K. Choi Thin Film Material Research Center, Korea Institute of Science and Technology, Seoul 136-701, Korea (Received 22 October 2007; accepted 7 January 2008)
Transmission electron microscopy (TEM) images, selected-area electron-diffraction patterns, high-resolution TEM images, and x-ray energy dispersive spectroscopy line scans for the ZnO/n-Si (001) heterostructures annealed at 900 °C showed that stacking faults and amorphous layers were formed in the lower region of the ZnO films. The stacking faults existing in the lower region of the ZnO columnar grains originated from the formation of zinc vacancy layers caused by the thermal treatment, resulting in the existence of a tensile strain. The formation of the amorphous layer in the ZnO film was attributed to the accumulation of zinc vacancy layers.
I. INTRODUCTION
Recently, II-VI thin films based on wide-band-gap semiconductor compounds have attracted considerable attention because of their potential applications in optoelectronic devices operating in the short-wavelength region.1,2 Among these II-VI thin films, ZnO materials have been very attractive because of interest in investigating fundamental physical properties3 and potential applications in optoelectronic devices operating in the blue and the ultraviolet (UV) regions of the spectrum, such as light-emitting diodes4 and laser diodes.5 Because ZnO thin films are semiconductors with particularly large band gaps and with the superior properties of large exciton binding energies, high optical gain, and excellent chemical stabilities, they have potential applications in optoelectronic devices.6–11 ZnO/Si heterostructures are of particular interest in the integration of optoelectronic devices due to the large exciton binding energy of the ZnO thin film and the cost-effectiveness and the large size of the Si substrate.12 Studies of the microstructural properties of ZnO/Si heterostructures are necessary for a)
Address all correspondence to this author. e-mail: [email protected] DOI: 10.1557/JMR.2008.0141 1082 J. Mater. Res., Vol. 23, No. 4, Apr 2008 http://journals.cambridge.org Downloaded: 16 Mar 2015
optoelectronic devices based on Si substrates because the microstructural properties significantly affect the optical properties of the thin films that are necessary to fabricate high-efficiency optoelectronic devices. Furthermore, because thermal treatment is necessary for the fabrication processes of several kinds of optoelectronic devices, the role of the thermal annealing processes is very important in achieving high-performance devices.13–16 Even though some work concerning the effect of thermal annealing on the microstructural and the optical properties of ZnO/Si heterostructures has been performed,17,18 the effects of thermal treatment on the microstructural properties of the lower region in ZnO thin film
Data Loading...
