Band-gap tailoring of ZnO by means of heavy Al doping

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: Discussionmentioning

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

“…Competing with the BM shift is the bandgap renormalization, a many-body effect which is the result of electron-dopant interactions along with the Coulomb and exchange interactions between the conduction band electrons [15,26,40]. Based on Jain's model, in a heavily doped semiconductor, the bandgap renormalization can be described by [14,42] [21,22,37], the relative dielectric constant is 21.9 [43], and the values of Λ and N b are 1 [42].…”

Section: Bandgap Shiftmentioning

confidence: 99%

Structural, optical, and electrical properties of indium-doped cadmium oxide films prepared by pulsed filtered cathodic arc deposition

et al. 2013

TitleStructural, optical, and electrical properties of indium doped cadmium oxide films prepared by pulsed filtered cathodic arc deposition cm 2 /Vs, and transmittance over 80% (including the glass substrate) from 500-1500 nm. The optical bandgap of the films was found to be in the range of 2.7 to 3.2 eV using both the Tauc relation and the derivative of transmittance. The observed widening of the optical bandgap with increasing carrier concentration can be described well only by considering bandgap renormalization effects along with the Burstein-Moss shift for a nonparabolic conduction band.

Materials Science-Poland

“…The refractive index (n) is an important factor to fabricate the devices with good optical properties because the dispersion energy is dependent on to the optical transition and optical conductivity [29]. The value of refractive index for pure and Ag doped ZnO thin films were calculated by the equation 8 [30]:…”

Section: Resultsmentioning

confidence: 99%

Structural and optical properties of pure and Ag doped ZnO thin films obtained by sol gel spin coating technique

Ali

Farooq

Baig

et al. 2015

We have investigated the influence of Ag doping on zinc oxide thin films. Pure and Ag doped, preferentially oriented transparent zinc oxide thin films were prepared by sol gel technique on a glass substrate using diethyl amine as a stabilizer. The X-ray diffraction analysis revealed that the films with hexagonal wurtzite type structure were polycrystalline in nature with a preferred grain orientation in the 101 direction. The crystallite sizes decreased from 34 nm to 27 nm after silver doping. Both photoluminescence and optical transmission measurements showed that the band gap increased after the Ag doping. The structure and optical characterization studies clearly indicated the incorporation of Ag in ZnO. Hence, the observed increase in the optical band gap and decrease in crystallite size can be directly attributed to the effect of Ag ion incorporation into the ZnO lattice.