Ultraviolet emission enhancement in ZnO thin films modified by nanocrystalline TiO 2

Photoluminescence (PL) of ZnO thin films prepared on c-Al2O3substrates by pulsed laser deposition (PLD) are investigated. For all samples, roomtemperature (RT) spectra show a strong band-edge ultraviolet (UV) emission with a pronounced low-energy band tail. The origin of this UV emission is analyzed by the temperature dependence of PL spectra. The result shows that the UV emission at RT contains different recombination processes. At low temperature donor-bound exciton (D0X) emission plays a major role in PL spectra, while the free exciton transition (FX) gradually dominates the spectrum with increasing temperatures. It notes that at low temperature an emission band (FA) appears in low energy side of D0X and FX and can survive up to RT. Further confirmation shows that the origin of the band FA can be attributed to the transitions of conduction band electrons to acceptors (e, A0), in which the acceptor binding energy is estimated to be approximately 121 meV. It is concluded that at room temperature UV emission originates from the corporate contributions of the free exciton and free electrons-to-acceptor transitions.

Download Full-text

Growth of ZnO thin films exhibiting room-temperature ultraviolet emission by means of atmospheric pressure vapor-phase epitaxy

Journal of Materials Chemistry ◽

10.1039/b006656g ◽

2001 ◽

Vol 11 (2) ◽

pp. 262-263 ◽

Cited By ~ 19

Author(s):

Kouji Omichi ◽

Kazuhiko Kaiya ◽

Naoyuki Takahashi ◽

Takato Nakamura ◽

Shinji Okamoto ◽

...

Keyword(s):

Thin Films ◽

Vapor Phase ◽

Atmospheric Pressure ◽

Room Temperature ◽

Vapor Phase Epitaxy ◽

Zno Thin Films ◽

Ultraviolet Emission

Download Full-text

Synthesis of Well-aligned ZnO Nanowires Using Simple Physical Vapor Deposition without Catalysts or Additives

MRS Proceedings ◽

10.1557/proc-879-z3.21 ◽

2005 ◽

Vol 879 ◽

Author(s):

Lisheng Wang ◽

Xiaozhong Zhang ◽

Songqing Zhao ◽

Guoyuan Zhou ◽

Yueliang Zhou ◽

...

Keyword(s):

Thin Films ◽

Vapor Deposition ◽

Physical Vapor Deposition ◽

Growth Direction ◽

Hexagonal Structure ◽

Zno Nanowires ◽

Nanowire Arrays ◽

Zno Thin Films ◽

Ultraviolet Emission ◽

Strong Ultraviolet Emission

AbstractWell-aligned ZnO nanowires were synthesized by simple physical vapor deposition using c-oriented ZnO thin films as substrate without catalysts or additives. The synthesized ZnO nanowires have two typical average diameters: 60 nm in majority and 120 nm in minority. They are about 4ím in length and well aligned along the normal direction of the substrate. Most of the synthesized ZnO nanowires are single crystalline in a hexagonal structure and grow along the [001] direction. The c-oriented ZnO thin films control the growth direction. Photoluminescence spectrum was measured showing a single strong ultraviolet emission (380 nm). Such result indicates that the ZnO nanowire arrays can be applied to excellent optoelectronic devices.

Download Full-text

Room temperature ultraviolet emission from microcrystallite ZnO thin films

10.1117/12.667713 ◽

2006 ◽

Author(s):

Weiwei Dong ◽

Ruhua Tao ◽

Qingli Su ◽

Zanhong Deng ◽

Xiaodong Fang

Keyword(s):

Thin Films ◽

Room Temperature ◽

Zno Thin Films ◽

Ultraviolet Emission

Download Full-text

Annealing Temperature Dependence of Optical Properties of Sol-Gel ZnO Thin Films with Different Sol Aging Time

Journal of Nano Research ◽

10.4028/www.scientific.net/jnanor.48.211 ◽

2017 ◽

Vol 48 ◽

pp. 211-217 ◽

Cited By ~ 2

Author(s):

Ji Tao Li ◽

Ding Yu Yang ◽

Xing Hua Zhu

Keyword(s):

Thin Films ◽

Optical Properties ◽

Aging Time ◽

Annealing Temperature ◽

Urbach Energy ◽

Energy Gap ◽

Sol Gel ◽

Zno Thin Films ◽

Zno Films ◽

Ultraviolet Emission

ZnO thin films on glass substrates have been successfully fabricated by sol-gel method for various aging time and annealing temperature. X-ray diffraction (XRD) patterns showed the crystallites at (100), (002) and (101) plane of hexagonal wurtzite structure. Atomic force microscope (AFM) images were used to investigate the surface morphology. The transmittance, energy gap, Urbach energy and photoluminescence (PL) of samples were investigated to explore the effects of annealing temperature on optical properties of ZnO thin films under different sol aging time. The transmittance spectra of thin films aged for 24 hours and 48 hours revealed the enhanced transmittance in visible region as rising annealing temperature, also, the optical band gap of the samples increased and Urbach energy decreased. The photoluminescence (PL) spectra of samples aged for 24 hours and 48 hours were studied and found the increased ultraviolet emission at ~387 nm, and various decreased visible emissions with rising annealing temperature. Nevertheless, the excessive sol aging time for 72 hours deteriorated the optical characteristics of thin films, resulting in that transmittance, energy gap and ultraviolet emission declined, and visible emissions increased with rising annealing temperature. The optical performances of the ZnO films aged for different time have no the same dependence of annealing temperature.

Download Full-text