Enhancement of near-band-edge photoluminescence from ZnO films by face-to-face annealing

Wang, Y. G.; Lau, Shu Ping; Zhang, X. H.; Hng, Huey Hoon; Lee, H. W.; Yu, Siu Fung; Tay, Beng Kang

doi:10.1016/j.jcrysgro.2003.07.015

Cited by 134 publications

(65 citation statements)

References 34 publications

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“…Studies have shown that the defects on the surface and grain boundaries, for example, oxygen vacancies, on ZnO and TiO 2 can trap the photoexcited electrons or holes to cause the nonradiative recombination of charge carriers and thus a lower emission efficiency. [37][38][39] Here, the defects likely present on the surface of Ga 2 O 3 can also act as nonradiative centers that trap the photoexcited electrons from CdS QDs. It has been shown by Jangir et al that the surface defects formed on Ga 2 O 3 in a controlled annealing environment reduces the emission efficiency.…”

Section: Resultsmentioning

confidence: 99%

Cadmium Sulfide Quantum Dots Supported on Gallium and Indium Oxide for Visible‐Light‐Driven Hydrogen Evolution from Water

et al. 2014

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In this work, CdS quantum dots (QDs) supported on Ga2O3 and In2O3 are applied for visible-light-driven H2 evolution from aqueous solutions that contain lactic acid. With Pt as the cocatalyst, the H2 evolution rates on CdS/Pt/Ga2O3 and CdS/Pt/In2O3 are as high as 995.8 and 1032.2 μmol h(-1), respectively, under visible light (λ>420 nm) with apparent quantum efficiencies of 43.6 and 45.3% obtained at 460 nm, respectively. These are much higher than those on Pt/CdS (108.09 μmol h(-1)), Pt/Ga2O3 (0.12 μmol h(-1)), and Pt/In2O3 (0.05 μmol h(-1)). The photocatalysts have been characterized thoroughly and their band structures and photocurrent responses have been measured. The band alignment between the CdS QDs and In2O3 can lead to interfacial charge separation, which cannot occur between the CdS QDs and Ga2O3. Among the various possible factors that contribute to the high H2 evolution rates on CdS/Pt/oxide, the surface properties of the metal oxides play important roles, which include (i) the anchoring of CdS QDs and Pt nanoparticles for favorable interactions and (ii) the efficient trapping of photogenerated electrons from the CdS QDs because of surface defects (such as oxygen defects) based on photoluminescence and photocurrent studies.

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Section: Resultsmentioning

confidence: 99%

Cadmium Sulfide Quantum Dots Supported on Gallium and Indium Oxide for Visible‐Light‐Driven Hydrogen Evolution from Water

et al. 2014

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“…TRPL is a contactless Full Paper technique that can be used to characterize and understand recombination effects in numerous photovoltaic materials. [34] In fact, the PL intensity is proportional to the rate of radiative recombination. The PL decay tracks recombination of the minority carrier, even though this recombination is primarily due to nonradiative processes such as ShockleyRead-Hall (SRH) or Auger recombination.…”

Section: Trplmentioning

confidence: 99%

Structural, Optical, and Electrical Characterization of ZnO and Al‐doped ZnO Thin Films Deposited by MOCVD

Fragalà

Malandrino

Giangregorio

et al. 2009

Chemical Vapor Deposition

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A novel approach is used to deposit transparent Al-doped zinc oxide (AZO) films by metal-organic (MO) CVD using a Zn/Al safe, friendly to use, easily to handle, multimetal, liquid precursor source. Films are highly crystalline, (002) textured, and exhibit good transparency in the visible region (90%). The effects of Al doping on morphological, optical, and electrical performances are scrutinized. Al doping causes an energy gap (Eg) blue shift and a slight decrease in refractive index. Moreover, it favors sizeable changes in grain size and a surface integrity that are responsible for a reduced carrier mobility. Nevertheless, a minimum resistivity value of 5 Â 10 À2 V cm is obtained for thin ($150 nm) AZO films. Time resolved photoluminescence (TRPL) confirms the high crystal quality of deposited films. All features render present AZO films well suited for transparent conductive oxide (TCO) applications and suggest a great potential for the proposed fabrication method.

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“…The crystal properties of ZnO films strongly depend on the technology of the deposition and the conditions of the growth process as well as of the different post growth treatments [18]. Previously, different annealing schemes such as rapid thermal annealing [19], in-situ thermal an-www.pss-c.com nealing [20], and face-to-face annealing [21], were applied and their influence on structural, optical, morphological, and electrical properties of pure ZnO was revealed [22][23][24]. Also, several studies have focused on the influence of post-deposition annealing on the properties of polycrystalline ZnO, doped by In [25], As [26], Ni [27], Ag [28], Cu [29], Mg [30].…”

mentioning

confidence: 99%

Study of annealing influence on electrical and morphological properties of ZnO:Ga thin films

Khranovskyy

Großner

Lasorenko

et al. 2006

Phys. Status Solidi (c)

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In this study, the influence of thermal annealing in different ambients on the electrical and morphological properties of Ga-doped ZnO films with 1wt.% gallium acetylacetonate in the precursor mix is investigated systematically. As-grown samples were prepared on c-plane Al 2 O 3 by PEMOCVD with a substrate temperature of 300 o C and possess a resistivity of about 10 -2 Ω·cm. The annealing was realized in isochronal steps between 300 to 1000 o C for 1 hour in argon and air ambient, respectively. The resistivity of the films was found to be dependent on the annealing atmosphere. During annealing in air, the resisitivity increases monotically with an abrupt reduction at 800 o C, whereas the annealing in argon does not induce significant changes but results in two clear minima at 300 o C and 800 o C. These effects are explained with crystal improvement at low temperature (300 o C) and successive dopant activation at higher temperature (800 o C). Furthermore, an anomalous surface flattening at 800 o C was observed. The obtained results suggest that the annealing procedure does allow to decrease the resistivity and roughness of as-grown ZnO:Ga films, what would be beneficial for the application of PEMOCVD-grown ZnO thin films for the formation of abrupt junctions in p-n device structures.

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Enhancement of near-band-edge photoluminescence from ZnO films by face-to-face annealing

Cited by 134 publications

References 34 publications

Cadmium Sulfide Quantum Dots Supported on Gallium and Indium Oxide for Visible‐Light‐Driven Hydrogen Evolution from Water

Cadmium Sulfide Quantum Dots Supported on Gallium and Indium Oxide for Visible‐Light‐Driven Hydrogen Evolution from Water

Structural, Optical, and Electrical Characterization of ZnO and Al‐doped ZnO Thin Films Deposited by MOCVD

Study of annealing influence on electrical and morphological properties of ZnO:Ga thin films

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