Structural and Optical Properties of ZnO Nanotips Grown on GaN Using Metalorganic Chemical Vapor Deposition |
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| Authors: | J Zhong G Saraf H Chen Y Lu Hock M Ng T Siegrist A Parekh D Lee E A Armour |
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| Affiliation: | (1) Department of Electrical and Computer Engineering, Rutgers University, Piscataway, NJ 08854, USA;(2) Bell Laboratories, Lucent Technologies, Murray Hill, NJ 07974, USA;(3) Veeco TurboDisc, Somerset, NJ 08873, USA |
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| Abstract: | ZnO nanotips are grown on epitaxial GaN/c-sapphire templates by metalorganic chemical vapor deposition. X-ray diffraction
(XRD) studies indicate that the epitaxial relationship between ZnO nanotips and the GaN layer is (0002)ZnO||(0002)GaN and
(101̄0)ZnO||(101̄0)GaN. Temperature-dependent photoluminescence (PL) spectra have been measured. Sharp free exciton and donor-bound
exciton peaks are observed at 4.4 K with photon energies of 3.380 eV, 3.369 eV, and 3.364 eV, confirming high optical quality
of ZnO nanotips. Free exciton emission dominates at temperatures above 50 K. The thermal dissociation of these bound excitons
forms free excitons and neutral donors. The thermal activation energies of the bound excitons at 3.369 eV and 3.364 eV are
11 meV and 16 meV, respectively. Temperature-dependent free A exciton peak emission is fitted to the Varshni’s equation to
study the variation of energy bandgap versus temperature. |
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| Keywords: | ZnO metalorganic chemical vapor deposition (MOCVD) nanostructure temperature-dependent photoluminescence (PL) free excitonic emission x-ray diffraction (XRD) |
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