Synthesis and characterization of aluminum-doped CdO thin films by sol–gel process

Mendelsberg

Applied Surface Science

et al. 2013

Title AbstractIndium doped cadmium oxide (CdO:In) films with different In concentrations were prepared on low-cost glass substrates by pulsed filtered cathodic arc deposition (PFCAD). It is shown that polycrystalline CdO:In films with smooth surface and dense structure are obtained. In-doping introduces extra electrons leading to remarkable improvements of electron mobility and conductivity, as well as improvement in the optical transmittance due to the Burstein-Moss effect. CdO:In films on glass substrates with thickness near 230 nm show low resistivity of 7.23×10 -5 Ωcm, high electron mobility of 142 cm 2 /Vs, and mean transmittance over 80% from 500-1250 nm (including the glass substrate). These high quality pulsed arc-grown CdO:In films are potentially suitable for high efficiency multi-junction solar cells that harvest a broad range of the solar spectrum. Keywords:In doped cadmium oxide; pulsed filtered cathodic arc deposition; transparent conductors IntroductionTransparent conducting oxides (TCOs) have attracted much attention due to their tremendous importance in optical and electrical applications such as displays, touch-screens, thin film solar cell technology and for transparent conducting electrodes in general [1,2]. For solar cell applications, high mobility TCO contacts with a sheet resistance of <10 Ω/□ and an optical transmission >80% over the visible to near infrared wavelengths (bandgap >3 eV) can enhance the efficiency [3]. This is particularly effective for multi-junction solar cells which consist of different semiconductor stacks with appropriately matched bandgaps that are tuned to increase the spectral response over the entire solar spectrum [4]. Therefore, in addition to maintaining high conductivity, improving the visible to near infrared transparency of TCO films is of great importance for applications in high performance multi-junction solar cells.

Section: Methodsmentioning

confidence: 99%

Transparent and conductive indium doped cadmium oxide thin films prepared by pulsed filtered cathodic arc deposition

Mendelsberg

Applied Surface Science

et al. 2013

Materials Science-Poland

“…where m is a constant determining the nature of interband transitions, which may be allowed or forbidden transition between the top of the valence band to the bottom of the conduction band; the values of m: 2, 0.5, 3, 1.5 correspond to allowed direct transitions, allowed indirect transition, forbidden direct transition and forbidden indirect transition, respectively [17], A is the energy independent constant, E g is the optical band gap and α is the absorption coefficient. The plots of (αhν) 2 vs. hν are shown in Fig.…”

Section: Optical Propertiesmentioning

confidence: 99%

Growth of Zn1−x CdxO nanocrystalline thin films by sol-gel method and their characterization for optoelectronic applications

Munirah

Khan²,

Khan

et al. 2014

This paper describes the growth of Cd doped ZnO thin films on a glass substrate via sol-gel spin coating technique. The effect of Cd doping on ZnO thin films was investigated using X-ray diffraction (XRD), UV-Vis spectroscopy, photoluminescence spectroscopy, I-V characteristics and field emission scanning electron microscopy (FESEM). X-ray diffraction patterns showed that the films have preferred orientation along (002) plane with hexagonal wurtzite structure. The average crystallite sizes decreased from 24 nm to 9 nm, upon increasing of Cd doping. The films transmittance was found to be very high (92 to 95 %) in the visible region of solar spectrum. The optical band gap of ZnO and Cd doped ZnO thin films was calculated using the transmittance spectra and was found to be in the range of 3.30 to 2.77 eV. On increasing Cd concentration in ZnO binary system, the absorption edge of the films showed the red shifting. Photoluminescence spectra of the films showed the characteristic band edge emission centred over 377 to 448 nm. Electrical characterization revealed that the films had semiconducting and light sensitive behaviour.

“…It has n-type semiconducting and an optical band gap lies between (2.2-2.7) eV depending on the kind of technique used and the preparation condition of that method used [1][2][3] . These properties make CdO thin films very useful for applications, such as heat mirror, solar cells, antireflection coatings, nonlinear optics and gas sensors [4][5][6][7][8][9] . CdO thin films have been prepared by several techniques such as, reactive sputtering, R F magnetron sputtering, sol-gel dip coatings, chemical bath deposition and chemical spray pyrolysis [10][11][12][13][14][15][20][21][22][23][24] .…”

Section: Introductionmentioning

confidence: 99%

Effect of Substrate Temperature on Structural and Optical Properties of CdO Thin Films

Ali

2014

ILCPA

Thin films of CdO have been prepared by spray pyrolysis technique. XRD analysis reveals that all the prepared samples were polycrystalline and have preferred orientation along [111] orientation. The surface topography was determined by AFM which indicate that surface roughness and rms roughness were increased by the increasing of substrate temperature. The optical energy gap were determined and its value lies between (2.4-2.5) eV.