| Summary: | 碩士 === 國立臺灣科技大學 === 機械工程系 === 99 === A different approach for co-doping in ZnO using Al-N as dopant has been attempted to realize p-type ZnO. The effect of Al doped ZnO thin films were grown on sapphire (0 0 0 1) substrates using sol-gel method and annealing with ammonia ambient in order to obtained p-type Al doped ZnO:N thin films were subjected to X-ray diffraction (XRD), scanning electron microscopy (SEM), photoluminescence (PL), Raman spectroscopy and Hall measurements.
The XRD analysis reveals that all thin films have grown in the form of hexagonal Wurtzite structure with (0 0 0 2) preferential orientation. The FWHM of (0 0 0 2) peak increase till 3 mol % Al doped ZnO:N and increases for further addition of Al-N indicating incorporation of more impurities (dopants). Surface morphology of the films was analyzed using SEM. The PL spectra of three different concentration of p-type Al doped ZnO:N showed a strong UV emission band located at 3.32 eV, 3.33 eV, 3.34 eV respectively and a very weak infrared emission associated with free carrier recombination. Al an N incorporation induced a blue shift of optical band gap and quenching of the near-band-edge PL for thin film because of the band-filling effect of free carrier and nonradiative recombination.
In micro- Raman Scattering for doped ZnO film, An increase in the E2 (low) phonon wavenumber is ascribed to increased the Al_Zn^(3+) replaced on the Zn site and increase in the E2 (high) phonon wavenumber due to Al and N doped induced compressive stress. Multiple phonon behaviour was observed up to 3rd order. The electrical properties of Al doped ZnO:N thin films are p type, 3 mol% Al doped ZnO:N thin films with highest hole carrier concentration ~4.91×1018 cm-3, 2 mol% Al doped ZnO:N thin films with highest mobility ~59.0 cm2V-1s-1 and lowest resistivity 0.034 Ω-cm.
|
|---|
