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UNIVERSITY OF BUCHAREST
FACULTY OF PHYSICS Guest
2024-11-22 2:33 |
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Conference: Bucharest University Faculty of Physics 2006 Meeting
Section: Optics, Spectroscopy, Plasma and Lasers
Title:
p- type ZnO thin films grown by RF assisted Pulsed Laser Deposition
Authors:
G. Epurescu, G. Dinescu, A. Moldovan, S. Canulescu, R. Birjega, M. Dinescu
Affiliation:
National Institute for Laser, Plasma and Radiation Physics,
PO Box MG–16 Magurele, 077125 Bucharest, Romania
E-mail
george@ifin.nipne.ro
Keywords:
ZnO, p-type, laser, radiofrequency, plasma
Abstract:
The high exciton binding energy and band gap energy of ZnO thin films open the prospect of fabricating semiconductor lasers in the ultraviolet spectral range. A prerequisite for laser diode fabrication is highly p-doped ZnO which was not reproducibly obtained up to now. Without intentional doping ZnO exhibits n-type conduction. Several suggestions have been made about the nature of the donor causing n-type conduction. Intrinsic point defects, e.g. zinc interstitials, have been proposed to induce a shallow donor level. ZnO thin films have been obtained by radio-frequency assisted pulsed laser deposition. A Zn metallic target was used for ablation in an oxygen and nitrogen RF discharge. The electrical and morphological properties of the films grown on Si were study by AFM, XRD, absorption and Hall Effect measurements for different ratios between the nitrogen and oxygen content. The AFM images of all the as-grown ZnO films reveal a high quality surface sample with low values for the surface roughness and a sharp distribution of grains sizes as an effect of presence of the RF discharge which reduces the surface roughness. The XRD patterns for all samples exhibit only (002) and (004) peaks indicating that the c-axis is always oriented normal to the substrate surface. The films exhibit p-type conductivity with different mobility depending on the nitrogen/oxygen ratio. The Auger electron spectroscopy and X-ray Photoelectron Spectroscopy measurements did not reveal the presence of nitrogen on ZnO thin films surface.
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