Orientation Inversions in Polycrystalline CdS Bulk Crystals and Thin Films

ABSTRACTA new design for a thin film microtensile tester is presented. The strain is measured directly on the free-standing thin film from the displacement of laser spots diffracted from a thin grating applied to its surface by photolithography. The diffraction grating is two-dimensional, allowing strain measurement both along and transverse to the tensile direction. In principle, both Young's modulus and Poisson's ratio of a thin film can be determined. Ag thin films with strong <111> texture were tested. The measured Young moduli agreed with those measured on bulk crystals, but the measured Poisson ratios were low, most likely due to slight transverse folding of the film that developed during the test.

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Transition Metal-Doped ZnO: A Comparison of Optical, Magnetic, and Structural Behavior of Bulk and Thin Films

MRS Proceedings ◽

10.1557/proc-0957-k04-10 ◽

2006 ◽

Vol 957 ◽

Cited By ~ 1

Author(s):

William E. Fenwick ◽

Matthew H. Kane ◽

Zaili Fang ◽

Tahir Zaidi ◽

Nola Li ◽

...

Keyword(s):

Thin Films ◽

Transition Metal ◽

Optical Transmission ◽

Magnetic Hysteresis ◽

Structural Quality ◽

Bulk Crystals ◽

Transmission Measurements ◽

Doped Zno ◽

Metal Doped ◽

Metal Incorporation

ABSTRACTTransition metal-doped ZnO bulk crystals and thin films have been investigated to determine the effects of transition metal incorporation on optical, magnetic, and structural properties of ZnO. A modified melt growth technique was used to grow bulk Zn1-xMnxO, Zn1-xCoxO, and Zn1-xFexO. Optical transmission measurements show an apparent shift in absorption edge with increasing transition metal incorporation. Raman spectroscopy also shows increasing lattice disorder with increasing transition metal concentration. ZnO thin films doped with Ni, Co, and Gd were grown by metalorganic chemical vapor deposition (MOCVD). While the Co-doped thin films showed antiferromagnetic behavior, magnetic hysteresis was observed in the Ni-doped and Gd-doped thin films. Structural quality was verified with X-ray diffraction (XRD), and optical properties were investigated using room temperature photoluminescence (PL) and optical transmission measurements. Properties of ZnO:TM bulk crystals and thin films are compared and used to discuss possible origins of ferromagnetism in these materials.

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Low-Frequency Noise in “Graphene-Like” Exfoliated Thin Films of Topological Insulators

MRS Proceedings ◽

10.1557/opl.2011.1349 ◽

2011 ◽

Vol 1344 ◽

Author(s):

M. Z. Hossain ◽

S. L. Rumyantsev ◽

K. M. F. Shahil ◽

D. Teweldebrhan ◽

M. Shur ◽

...

Keyword(s):

Thin Films ◽

Topological Insulators ◽

Low Frequency ◽

Frequency Noise ◽

Low Frequency Noise ◽

Bulk Crystals ◽

Noise Spectral Density ◽

Noise Data ◽

Device Applications ◽

Surface Conduction

ABSTRACTWe report results of the study of the low-frequency noise in thin films of bismuth selenide topological insulators, which were mechanically exfoliated from bulk crystals via “graphene-like” procedures. From the resistance dependence on the film thickness, it was established that the surface conduction contributions to electron transport were dominant. It was found that the current fluctuations have the noise spectral density SI ∞ 1/f (where f is the frequency) for the frequency range up to 10 kHz. The obtained noise data are important for transport experiments with topological insulators and for any proposed device applications of these materials.

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