Photoluminescence and ultraviolet laser emission from nanocrystalline ZnO thin films

Mitra, Anirban; Thareja, R. K.

doi:10.1063/1.1342803

Cited by 106 publications

(53 citation statements)

References 20 publications

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“…The scintillation risetime in ZnO:Fe was 38 ps, while the decay time consisted of two components (2.1 and 70 ps). Studies aimed at creating a ZnO-based UV laser are progressing, and induced radiation has been obtained for p-n-transitions and in thin films [54].…”

Section: Practice-oriented Studies Of Zno Thin Films Powders and Simentioning

confidence: 99%

Optical and luminescence properties of zinc oxide (Review)

Родный¹,

Khodyuk²

2011

Opt. Spectrosc.

369

187

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Abstract-We generalize and systematize basic experimental data on optical and luminescence properties of ZnO single crystals, thin films, powders, ceramics, and nanocrystals. We consider and study mechanisms by which two main emission bands occur, a short-wavelength band near the fundamental absorption edge and a broad long-wavelength band, the maximum of which usually lies in the green spectral range. We determine a relationship between the two luminescence bands and study in detail the possibility of controlling the characteristics of ZnO by varying the maximum position of the short-wavelength band. We show that the optical and luminescence characteristics of ZnO largely depend on the choice of the corresponding impurity and the parameters of the synthesis and subsequent treatment of the sample. Prospects for using zinc oxide as a scintillator material are discussed. Additionally, we consider experimental results that are of principal interest for practice.

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Section: Practice-oriented Studies Of Zno Thin Films Powders and Simentioning

confidence: 99%

Optical and luminescence properties of zinc oxide (Review)

Родный¹,

Khodyuk²

2011

Opt. Spectrosc.

369

187

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“…However, a broad and relative strong green emission centered at 558 nm was observed for sample 3, while a 413 nm visible emission was detected for sample 4. Generally, the UV emission band is originated from the direct recombination of the free excitons through an exciton-exciton collision process [17][18], while the visible emission is due to the impurities and structure defects in ZnO crystals [19][20]. These results indicate that the as-obtained ZnO nanorod assemblies have fairly good crystal quality and the prepared sheet-based ZnO nanoarchitectures have more structural defects.…”

Section: Methodsmentioning

confidence: 71%

Shape‐controlled synthesis of ZnO architectures

Wang¹,

Song

2007

Cryst. Res. Technol.

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Several ZnO nanoarchitectures have been selectively prepared through hydrothermal method including urchin-shaped, flower-shaped, butterfly-shaped, and cacti-shaped microstructures. The influence of reaction temperature and the concentration of amphiphilic copolymer on the morphologies and shapes of ZnO samples have been studied. The samples were characterized using XRD, TEM, and SEM. It was found that ZnO nanorods or their assemblies were fabricated at higher temperature, whereas ZnO nanosheet architectures were produced at lower temperature. These flower-shaped architectures possess high BET surface area of 27.43 m 2 /g. Room temperature UV-VIS and PL spectra of the as-obtained ZnO nanoarchitectures have been examined.

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“…Zinc oxide (ZnO) is a wide energy bandgap semiconductor that has potential applications for photodetectors, 1,2 light-emitting diodes, lasers, 3,4 and modulators 5 operating in the ultraviolet range. The direct bandgap of ZnO can be tuned from 3.3 eV to 4.0 eV by alloying ZnO with MgO to form the ternary compound, magnesium zinc oxide (Mg x Zn 1Ϫx O).…”

Section: Introductionmentioning

confidence: 99%

Nonalloyed Al ohmic contacts to MgxZn1−xO

Sheng

Emanetoglu

Muthukumar

et al. 2002

Journal of Elec Materi

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INTRODUCTIONZinc oxide (ZnO) is a wide energy bandgap semiconductor that has potential applications for photodetectors, 1,2 light-emitting diodes, lasers, 3,4 and modulators 5 operating in the ultraviolet range. The direct bandgap of ZnO can be tuned from 3.3 eV to 4.0 eV by alloying ZnO with MgO to form the ternary compound, magnesium zinc oxide (Mg x Zn 1Ϫx O). The ZnO/Mg x Zn 1Ϫx O heterostructure is promising for a wide range of electronic and photonic devices. 6,7 Metal/Mg x Zn 1Ϫx O contacts, including ohmic and Schottky types, play important roles in device performance. In the case of ohmic-contact technology, nonalloyed ohmic contact with low specific contact resistance is preferred, particularly for shallow junction and low voltage devices, as it provides smooth metal-semiconductor interfaces resulting from the limited interface reaction. In this paper, we report the results of Al nonalloyed ohmic contacts on epitaxial Mg x Zn 1Ϫx O (0 Յ ϫ Յ 0.34) thin films. EXPERIMENTALZnO and Mg x Zn 1Ϫx O films (200-500 nm) were grown on R-plane sapphire (R-Al 2 O 3 ) substrates using metal organic chemical vapor deposition (MOCVD). The R-plane sapphire was chosen as a substrate instead of the commonly used C-plane sapphire as it offers two advantages: (1) the c-axis of ZnO lies in the surface plane, with the lattice mismatch parallel to the c-axis of ZnO being lower than the mismatch perpendicular to the c-axis (1.53% versus 18.3%), resulting in overall less mismatch; and (2) in-plane anisotropy in the ZnO/R-Al 2 O 3 system can be used to make novel optical, electrical, and piezoelectric devices. 8 The composition of the Mg x Zn 1Ϫx O films were evaluated using the Rutherford backscattering spectroscopy (RBS) technique. The surface morphology was inspected using fieldemission scanning electron microscopy (FESEM). Xray diffraction (XRD) was used to analyze the crystallinity of the material. After the growth of the Mg x Zn 1Ϫx O films, metal layers (Al/Au: 100 nm/100 nm) were deposited using an electron-beam evaporator to form the nonalloyed ohmic contacts. Aluminum was chosen as the ohmic contact metal because of its low barrier height on ZnO. 9 Gold was used as a cover layer to prevent the surface oxidation after the contact formation, as well as for bonding. The transmission line method (TLM) was used to measure the specific contact resistances. The linear TLM metallization pattern consists of seven square contact pads (area 80 ϫ 80 m 2 ), separated by different spacing, Al nonalloyed ohmic contacts were fabricated and characterized on Mg x Zn 1-x O (0 Յ ϫ Յ 0.34) epilayers, which were grown on R-plane sapphire substrates by metal organic chemical vapor deposition (MOCVD). Specific contact resistances were evaluated by the transmission line method (TLM). A specific contact resistance of 2.5 ϫ 10 Ϫ5 ⍀cm 2 was obtained for Al contact to ZnO with an electron concentration of 1.6 ϫ 10 17 cm Ϫ3 . The current flow mechanism was studied by investigating the dependence of specific contact resistances on electron concentra...

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Photoluminescence and ultraviolet laser emission from nanocrystalline ZnO thin films

Cited by 106 publications

References 20 publications

Optical and luminescence properties of zinc oxide (Review)

Optical and luminescence properties of zinc oxide (Review)

Shape‐controlled synthesis of ZnO architectures

Nonalloyed Al ohmic contacts to MgxZn1−xO

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