Effects of sputtering-deposition inclination angle on the IGZO film microstructures, optical properties and photoluminescence

Tse Chang Li, Chang Fu Han, Ta Hsuan Kuan, Jen Fin Lin

Research output: Contribution to journalArticle

6 Citations (Scopus)

Abstract

IGZO/PET specimens were respectively prepared with 0°, 15°, 30°, 45°, and 60° as the inclination angle of the thin film deposition. The ntype conductivity was identified in these specimens. The following parameters, including the film thickness and morphologies of the top and lateral surfaces, the mechanical properties, chemical compounds and their primary lattices in X-ray diffraction (XRD) patterns, and the X-ray photoelectron spectrometries (XPS) for Ga2p, Ga3d, In3d, Zn2p, and O1s are presented. IR is defined as the intensity ratio of the InGaO3(ZnO)3 peak value to the sum of the peak values of InGaO3(ZnO)3 and InGaZnO4. Decompositions of the O1s and Ga3d spectra provide nearly Gaussian profiles of Ga-Ga, In4d, Ga-O, O1, O2, and O3. The O2 intensity ratio IRO2, which is defined as the ratio of O2 peak intensity to the peak intensity sum of O1 and O2, was evaluated for these five specimens. Depth profiles of the distributions of O, Zn, Ga, and In ions were obtained by secondary ion mass spectrometry (SIMS), and the slope (Go) of the O-ion profile in the decaying region was obtained as a function of inclination angle. Increases in the inclination angle can effectively reduce surface roughness. The peak intensities of Ga2p, Ga3d, In3d, Zn2p, and O1s formed in the specimen preparations with a nonzero inclination angle were always lower than those of the IGZO_0° specimen. Although an increase in inclination angle can raise the IRO2 value, a nonzero inclination angle yielded an IR value lower than that of the IGZO_0° specimen. Moreover, the IRO2 value increased with (negative) Go decrease as the response. The combined result of increasing IRO2 and the In-O and Ga-O bonds, and decreasing the IGZO film thickness can increase light transmission. Specimens with a larger surface roughness result in a higher reflection. The IR parameter for the specimens with a nonzero inclination angle has a value smaller than that of the IGZO_0° specimen; as such, an increase in IR is advantageous for increasing the n-type conductivity. The decreasing rate of extinction coefficient k with respect to wavelength in the visible light region increases significantly with increasing IRO2. IR and IRO2 are therefore the governing factors of the peak intensities for the three decomposed profiles of microphotoluminescence (PL). Increasing IR and IRO2 or decreasing film thickness is advantageous for increasing the PL peak intensities. Increases in the product values of IR and IRO2 are favorable for increasing the peak intensities of violet and ultraviolet.

Original languageEnglish
Pages (from-to)343-366
Number of pages24
JournalOptical Materials Express
Volume6
Issue number2
DOIs
Publication statusPublished - 2016 Jan 1

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials

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