Photoacoustic Spectra from Co Doped ZnO with Different Grain or Cluster Sizes

Inoué, Yoshihiro; Miyauchi, Yoshiko; Kimura, Akitsugu; Kawahara, Toshio; Okamoto, Yoshio; Morimoto, Jun

doi:10.1143/jjap.43.2936

Cited by 16 publications

(16 citation statements)

References 18 publications

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“…During the light irradiation, phenomenon of photodesorption of water molecule through the electronic excitation [42,43], light induced heat [44] and vibration [45] takes place. The slow photodesorption of water molecules leads to the slow decrease of conductivity.…”

Section: Rise and Decay Of Photocurrentmentioning

confidence: 99%

Photoconductivity and photoluminescence of ZnO nanoparticles synthesized via co-precipitation method

Kripal

Gupta

Srivastava

et al. 2011

Spectrochimica Acta Part A: Molecular and Biomolecular Spectros

119

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Section: Rise and Decay Of Photocurrentmentioning

confidence: 99%

Photoconductivity and photoluminescence of ZnO nanoparticles synthesized via co-precipitation method

Kripal

Gupta

Srivastava

et al. 2011

Spectrochimica Acta Part A: Molecular and Biomolecular Spectros

119

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“…PA spectroscopy can be used to determine the band gap as shown in refs 31,34,37 as well as the impurity and defect-related absorption 33,35 . Moreover, this technique can be used to study the surface and bulk nonradiative recombination 32 and the thermal diffusivity 36 .…”

Section: Introductionmentioning

confidence: 99%

Photoacoustic and modulated reflectance studies of indirect and direct band gap in van der Waals crystals

Zelewski

Kudrawiec

2017

Sci Rep

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Photoacoustic (PA) and modulated reflectance (MR) spectroscopy have been applied to study the indirect and direct band gap for van der Waals (vdW) crystals: dichalcogenides (MoS 2 , MoSe 2 , MoTe 2 , HfS 2 , HfSe 2 , WS 2 , WSe 2 , ReS 2 , ReSe 2 , SnS 2 and SnSe 2 ) and monochalcogenides (GaS, GaSe, InSe, GeS, and GeSe). It is shown that the indirect band gap can be determined by PA technique while the direct band gap can be probed by MR spectroscopy which is not sensitive to indirect optical transitions. By measuring PA and MR spectra for a given compound and comparing them with each other it is easy to conclude about the band gap character in the investigated compound and the energy difference between indirect and direct band gap. In this work such measurements, comparisons, and analyses have been performed and chemical trends in variation of indirect and direct band gap with the change in atom sizes have been discussed for proper sets of vdW crystals. It is shown that both indirect and direct band gap in vdW crystals follow the well-known chemical trends in semiconductor compounds.Van der Waals (vdW) crystals are known for a long time 1-14 but in recent years some of them have gained significant interest because of unique mechanical and optical properties of samples obtained by exfoliation of bulk material to atomically thin layers [15][16][17][18][19][20][21][22][23][24][25] . Since pioneering reports on optical properties of MoS 2 layers 15,16 , it is well established that the electronic band structure of MoS 2 strongly varies with the number of layers and exhibits indirect-to-direct band gap transition with the size reduction to a single layer. Similar studies of optical properties and the electronic band structure have been performed on other van der Waals crystals such as MoSe 2 , MoTe 2 , WS 2 , and WSe 2 22-25 . Some of them were investigated quite recently as bulk materials 13,14 but interest in these materials was low due to no potential applications in semiconductor devices. At this moment the situation is different. VdW crystals are exciting because of interesting physics of two-dimensional (2D) layers and their potential applications in novel semiconductor devices [26][27][28] . Because of this even bulk van der Waals crystals are interesting to study since many of them are not explored experimentally. One method which has never been applied to study most of van der Waals crystals is photoacoustic (PA) spectroscopy. We show that this technique is an excellent tool to study the band gap in van der Waals crystals since it is sensitive to indirect gap transitions which cannot be observed in photoluminescence. In combination with modulated reflectance (MR), which is known as a state of the art absorption-like technique to study direct optical transitions 29 , it is possible to conclude about the band gap character in van der Waals crystals and the spectral separation between the indirect and direct gap. In this work we applied PA and MR to study indirect and direct gap in many van der Waals crystals ...

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“…Changes of sample temperature by photothermal phenomenon (proportional to optical absorption) generate pressure changes in the enclosed gas that are converted to electrical signal by the microphone. The application of PA spectroscopy for the characterization of the electronic, optical, defect structures and thermal properties of semiconductors is important and has been demonstrated [9][10][11][12][13][14][15][23][24][25][26][27][28][29][30]. IPCE spectroscopy is a photoelectrochemical technique and it can evaluate the total quantum yield for (1) the electron injection from the CdSe QDs to the conduction band of TiO 2 , (2) the collection efficiency of the injected electrons at the back contact and (3) the hole transfer efficiency to the electrolyte.…”

Section: Introductionmentioning

confidence: 99%

Correlation between crystal growth and photosensitization of nanostructured TiO2 electrodes using supporting Ti substrates by self-assembled CdSe quantum dots

2008

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Photoacoustic Spectra from Co Doped ZnO with Different Grain or Cluster Sizes

Cited by 16 publications

References 18 publications

Photoconductivity and photoluminescence of ZnO nanoparticles synthesized via co-precipitation method

Photoconductivity and photoluminescence of ZnO nanoparticles synthesized via co-precipitation method

Photoacoustic and modulated reflectance studies of indirect and direct band gap in van der Waals crystals

Correlation between crystal growth and photosensitization of nanostructured TiO2 electrodes using supporting Ti substrates by self-assembled CdSe quantum dots

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