Cathodoluminescence Intensity Research Articles

A carbon fiber-ZnS nanocomposite for dual application as an efficient cold cathode as well as a luminescent anode for display technology.

In the current work we present a simple technique to develop a carbon nanofiber (CNF)/zinc sulfide (ZnS) composite material for excellent FED application. CNFs and ZnS microspheres were synthesized by following a simple thermal chemical vapor deposition and hydrothermal procedure, respectively. A rigorous chemical mixture of CNF and ZnS was prepared to produce the CNF-ZnS composite material. The cathodo-luminescence intensity of the composite improved immensely compared to pure ZnS, also the composite material showed better field emission than pure CNFs. For pure CNF the turn-on field was found to be 2.1 V μm(-1) whereas for the CNF-ZnS composite it reduced to a value of 1.72 V μm(-1). Altogether the composite happened to be an ideal element for both the anode and cathode of a FED system. Furthermore, simulation of our CNF-ZnS composite system using the finite element modeling method also ensured the betterment of field emission from CNF after surface attachment of ZnS nanoclusters.

Luminescent properties, intensity degradation and X-ray photoelectron spectroscopy analysis of CaS:Eu2+ powder

In the present work, we report the structure, particle morphology, surface chemical states, photoluminescent properties and cathodoluminescence intensity degradation of the CaS:Eu2+ powder phosphors. X-ray diffraction, X-ray photoelectron spectroscopy, and photoluminescence (PL) spectroscopy data suggest that the powder contains secondary phases that were possibly formed during the preparation or due to unintended contamination. These phases presented an opportunity to demonstrate the dependence of the emission of the Eu2+ ion on the host lattice. An intense red PL broad band with a maximum at 650nm was observed when the powder was excited at 484nm using a monochromatized xenon lamp. When the powder was excited using a 325nm He–Cd laser an additional PL emission peak was observed at 384nm. The origin of this emission is discussed. Auger electron spectroscopy and Cathodoluminescence (CL) spectroscopy were used to monitor the changes in the surface chemical composition and CL intensity of the CaS:Eu2+ phosphors when the phosphor was irradiated with a 2keV electron beam in vacuum. The CL degradation is attributed to, among other things, the formation of a non-luminescent layer of CaSO4, surface charging, and possibly the presence of O defects. This phosphor is evaluated for applications in low voltage field emission displays and light emitting diodes.

Positron annihilation and cathodoluminescence study on inductively coupled plasma etched GaN

AbstractEtching damage induced by inductively coupled plasma (ICP) with a mixture of Cl and BCl gases and the effect of subsequent annealing in Nwere studied through positron annihilation and cathodoluminescence (CL) for Mg‐doped and Si‐doped GaN. The changes in the concentration of nonradiative defects and in the shape of band bending caused by ICP etching or subsequent annealing were studied by comparing the CL intensities and the diffusion lengths of implanted positrons, respectively. For Mg‐doped GaN, CL spectra revealed that etching inactivated the Mg acceptors at the near‐surface region. After annealing at 900 °C, the Mg acceptors were reactivated. For Si‐doped GaN, etching introduced neutral vacancy‐type defects, and after annealing at 900 °C, the etching‐induced defects almost disappeared. However, there were residual nonradiative defects on the top surface that were associated with a change in the surface's Fermi level position.

Influence of CVD process duration on morphology, structure and sensing properties of carbonaceous-palladium films

We present the nanocomposite carbonaceous-palladium (C-Pd) thin films prepared by physical vapor deposition (PVD) and chemical vapor deposition (CVD) methods. Scanning electron microscope (SEM) and transmission electron microscope (TEM) methods were used to study the topography, morphology and structure of carbon and palladium nanograins contained in these films. The quantitative analysis of the elemental composition of C-Pd films was determined by energy-dispersive spectroscopy (EDS). The initial PVD films were modified in a CVD quartz reactor using xylene (the mixture of isomers) as a modifying factor at different times (5, 10 and 30 minutes) at a constant temperature of 650°C in atmospheric pressure. It was observed that the average size of palladium nanograins increased with an increasing duration of modification process. The differences in microstructures observed in the CVD films modified at different times, affect their response in measurements of resistance changes in the gas containing H2 in various concentrations. All samples were measured by cathodoluminescence (CL) method. In CL studies a large amount of objects with high intensity of CL was found. Some of them show the emission bands both at 450 nm and 750 nm. Other reveals emission band only at 450 nm. CL observations show that Pd nanograins coated by graphite shells exhibit optical activity.

Using nanoindentation and cathodoluminescence to investigate the residual stress of ZnSe

In this study we examined the effects of the nanoindentation-induced residual stress of single-crystalline zinc selenide (ZnSe). We employed the nanoindentation technique to evaluate the dislocation mobility of ZnSe at loading ratios of 10 and 2mN/min, with a holding time of 120s under a constant load. We visualized the resultant dislocation and microcracks using cathodoluminescence (CL) spectroscopy and mapping to compare the nanoindentation-induced residual stresses of the various ZnSe samples. CL mapping revealed massive dislocation activities during the loading process. The dislocations played roles as nonradiative recombination centers that quenched the local CL intensity. Transmission electron microscopy also revealed the effects of nanoindentation-induced residual stress. To obtain insight into the influence of the residual stress and to determine the dislocation mobilities for ZnSe films, it was essential to monitor the quenching effect of nonradiative recombination centers as a function of CL mapping.

Cathodoluminescence Analysis of Grain Boundaries and Grain Interiors in Thin-Film CdTe

We used low-temperature cathodoluminescence (CL) spectrum imaging (CLSI) with nanoscale spatial resolution to examine charge-carrier recombination and defects at grain boundaries (GBs) and grain interiors (GIs) in as-deposited and CdCl 2 -treated CdTe thin films. Supporting time-resolved photoluminescence, T = 4 K photoluminescence, secondary ion mass spectrometry, and electron backscatter diffraction measurements were conducted on the same films. Color-coded maps of the luminescence transition energies (photon energy maps) were used to analyze the qualitative characteristics of the CLSI data. We applied an image analysis algorithm to the pixels in grayscale CL intensity images to compare the luminescence intensities and spectra at the GIs and GBs quantitatively and with statistical relevance. Our results show that GBs in as-deposited films are active recombination centers and are thus harmful to solar cell operation. CL GB defect contrast is quantifiably reduced for the CdCl 2 -treated film, which is direct evidence of passivation of deep GB core states resulting from the treatment. However, the CdCl 2 treatment is not a perfect fix for GB recombination, and GB recombination may still be limiting performance in CdCl 2 -treated devices.

Visualization of oxygen off-stoichiometry in oxide ceramics by cathodoluminescence spectroscopy

In this study, we used cathodoluminescence (CL) to investigate the influence of annealing treatments with different temperatures and atmospheres on oxygen vacancy concentrations in two paradigmatic ceramic oxides, yttria-stabilized cubic zirconia and alumina. Significant stoichiometric differences were seen for surfaces exposed to either oxidizing or reducing atmospheres by comparison with the respective as-sintered samples. In the case of zirconia, monitoring the CL band located at 500nm enabled us to visualize the trends of oxygen vacancy formation or annihilation, depending on the annealing conditions selected. In the case of alumina, CL mapping could reveal different processes of oxygen vacancy formation, annihilation and migration (towards grain boundaries) as a consequence of annealing procedures conducted in different gas mixtures. Monitoring the CL intensity of the F+-center in alumina made it possible to assess the complex stoichiometric state developing at the joint interface between a metal and polycrystalline alumina with nanometric resolution.

Influence of radiation damage on Late Jurassic zircon from southern China: Evidence from in situ measurements of oxygen isotopes, laser Raman, U–Pb ages, and trace elements

The influence of radiation damage on chemical alteration and in situ elemental and isotopic analyses in zircons is evaluated in three ~155Ma granites that are associated with W–Sn polymetallic deposits in the Nanling area of southern China. A combined approach is described using SEM imaging, laser Raman spectroscopy, and ion microprobe analysis of oxygen isotope ratios, U–Pb ages, and trace elements, including H. Domains within single zircons can be classified into two groups based on cathodoluminescence (CL) intensity and U–Th concentrations. Type-I are single crystals or clearly defined cores with bright CL, having U<1400ppm and Th<800ppm; type-II are rims surrounding type-I cores or single crystals with dark or intermediate CL-intensity and have 2100–30,000ppm U and 900–6500ppm Th. Both types of zircon display oscillatory zonation. Type-I zircons show a narrow range of δ18Ozircon values (8.5–9.2‰), while type-II zircons have much greater variation of apparent δ18Ozircon values (1.4–8.6‰). Relative to type-I, type-II zircons are characterized by elevated trace-element concentrations (including U, Th, rare earth elements, Y, Hf, Fe and Ti, LaN>10), high cumulative α-dose and background-corrected 16OH/16O, decreased Th/U and Hf/Yb ratios, and deviation in 206Pb/238U ages (up to 70Ma) from the mean age (ca. 155Ma) of type-I zircons. Moreover, laser Raman results show that type-II zircons have much broader FWHM (full width half maximum=6.3–37.8cm−1) and decreased amplitudes for the ~1005cm−1 Raman peak, indicating that they are affected by significant radiation damage. The Raman-measured preserved radiation damage (DαP=0.01–0.49×1015α-decay events/mg) is less than the total alpha-dose (DαT=0.1–1.72×1015α-decay events/mg) for each zircon of type-I and type-II with FWHM<10cm−1, indicating that 30–80% of the total radiation damage experienced by most of these zircons has been annealed. We attribute the negative correlation of δ18O versus U, Th, Y, Hf, La and cumulative α-dose for type-II zircons to open-system behavior resulting from radiation damage of the zircon crystal structure. We interpret type-II zircons to originally represent crystallization from a late-stage granite melt that was enriched in magmatic fluids and incompatible elements. The wide range and low δ18O values recorded by most type-II zircon domains are the result of secondary alteration by fluids (perhaps hydrothermal) facilitated by radiation damage and open system chemical and isotopic exchange. This work shows that a combined approach using imaging, laser Raman and trace element analysis is effective for evaluating the influence of radiation damage and alteration of zircon. This protocol is necessary to evaluate the reliability of in situ oxygen isotopic and U–Pb ages. The 16OH/16O ratio is readily measured during SIMS analysis of oxygen isotopes and can be an effective parameter to monitor alteration of radiation-damaged domains in zircon.

A polarity-driven nanometric luminescence asymmetry in AlN/GaN heterostructures

Group III Nitrides nanowires are well suited materials for the design of light emitting devices. The internal electric field created by spontaneaous and piezoelectric polarizations in these materials poses some difficulties, but also possible solutions, towards this goal. Here, we report on the high spatial asymmetry of the cathodoluminescence intensity across a GaN quantum well embedded in an AlN nanowire, when a 60 keV, 1 nm wide electron beam is scanned over this heterostructure. This asymmetry is remarkable between positions at different sides of the quantum well. We interpret this asymmetry as originating from the different drift directions of carriers due to the internal electric field. This interpretation is corroborated by the direct determination of the polarity with convergent beam electron diffraction. A precise knowledge of hole mobility and diffusion coefficients would allow an estimate of the electric field in the AlN segment of the nanowire.

Hydrocarbon film formed on the surface of a semiconductor irradiated by an electron beam

The rate of formation of a hydrocarbon film on the surface of a sample subjected to the action of an electron beam is studied at room temperature and in cooling a sample to the liquid nitrogen temperature. The thickness and the optical radiation transmission of such films are measured as functions of the electron beam radiation time, the sample temperature, and the level of vacuum. The film thickness is measured with atomic force microscopy. The absorption of the films is determined by comparing the cathodoluminescence intensities from a pure sample surface and from the surface covered with a film. The experimental results can be used to estimate the film formation rate as a function of the sample temperature and the vacuum and to determine the optical radiation absorption at a wavelength of 300, 360, 550, and 665 nm.

Optical detection of spin-filter effect for electron spin polarimetry

We have monitored the cathodoluminescence (CL) emitted upon injection of free electrons into a hybrid structure consisting of a thin magnetic Fe layer deposited on a p-GaAs substrate, in which InGaAs quantum wells are embedded. Electrons transmitted through the unbiased metal/semiconductor junction recombine radiatively in the quantum wells. Because of the electron spin-filtering across the Fe/GaAs structure, the CL intensity, collected from the backside, is found to depend on the relative orientation between the injected electronic spin polarization and the Fe layer magnetization. The spin asymmetry of the CL intensity in such junction provides a compact optical method for measuring spin polarization of free electrons beams or of hot electrons in solid-state devices.

Bias dependence and correlation of the cathodoluminescence and electron beam induced current from an InGaN/GaN light emitting diode

Micron-scale mapping has been employed to study a contacted InGaN/GaN LED using combined electroluminescence (EL), cathodoluminescence (CL), and electron beam induced current (EBIC). Correlations between parameters, such as the EBIC and CL intensity, were studied as a function of applied bias. The CL and EBIC maps reveal small areas, 2–10 μm in size, which have increased nonradiative recombination rate and/or a lower conductivity. The CL emission from these spots is blue shifted, by 30–40 meV. Increasing the reverse bias causes the size of the spots to decrease, due to competition between in-plane diffusion and drift in the growth direction. EL mapping shows large bright areas (∼100 μm) which also have increased EBIC, indicating domains of increased conductivity in the p and/or n-GaN.

Enhanced Cathodoluminescence of KOH-treated InGaN/GaN LEDs with Deep Nano-Hole Arrays

Square lattice nano-hole arrays with diameters and periodicities of 200 and 500 nm, respectively, are fabricated on InGaN/GaN blue light emitting diodes (LEDs) using electron-beam lithography and inductively coupled plasma reactive ion etching processes. Cathodoluminescence (CL) investigations show that light emission intensity from the LEDs with the nano-hole arrays is enhanced compared to that from the planar sample. The CL intensity enhancement factor decreases when the nano-holes penetrate into the multiple quantum wells (MQWs) due to the plasma-induced damage and the residues. Wet chemical treatment using KOH solution is found to be an effective method for light extraction from the nano-patterned LEDs, especially, when the nano-holes penetrate into the MQWs. About 4-fold CL intensity enhancement factor is achieved by the KOH treatments after the dry etching for the sample with a 250-nm deep nano-hole array.

Crystallisation of magmatic topaz and implications for Nb–Ta–W mineralisation in F-rich silicic melts — The Ary-Bulak ongonite massif

Textural, mineralogical and geochemical data on F-rich rhyolite (ongonite) from the Ary-Bulak massif of eastern Transbaikalia help constrain the formation of magmatic topaz. In these rocks, topaz occurs as phenocrysts, thus providing compelling evidence for crystallisation at the orthomagmatic stage. Cathodoluminescence images of topaz and quartz reveal growth textures with multiple truncation events in single grains, indicative of a dynamic system that shifted from saturated to undersaturated conditions with respect to topaz and quartz. Electron microprobe and Raman analyses of topaz indicate near-pure F composition [Al2SiO4F2], with very limited OH replacement. Laser ablation ICP-MS traverses revealed the presence of a large number of trace elements present at sub-ppm to hundreds of ppm levels. The chemical zoning of topaz records trace element fluctuations in the coexisting melt. Concentrations of some trace elements (Li, Ga, Nb, Ta and W) are correlated with cathodoluminescence intensity, thus suggesting that some of these elements act as CL activators in topaz. The study of melt inclusions indicates that melts with different F contents were trapped at different stages during formation of quartz and topaz phenocrysts, respectively. Electron microprobe analyses of glass in subhedral quartz-hosted melt inclusions indicate F ≤ 1.2 wt.%, whereas irregular-shaped melt inclusions hosted in both topaz and quartz have F ≤ 9 wt.%. Cryolithionite [Na3Li3Al2F12] coexists with glass in irregular inclusions, implying high Li contents in the melt. The very high F contents would have increased the solubility of Nb, Ta and W in the melt, thus allowing progressive concentration of these elements during magma evolution. Crystallisation of Nb–Ta–W-oxides (W-ixiolite and tantalite–columbite) may have been triggered by separation of cryolithionite, which would have caused F and Li depletion and consequent drop in the solubility of these elements.

Luminescence of CNT coated LaPO4:Tm phosphors and their field emission lamp application

When the phosphor LaPO4:Tm was coated with carbon nanotubes (CNTs), carbon atoms were diffused into the phosphor lattice. Binding energy of La 3d and C 1s were not shifted by CNT coating, while that of O 1s was lowered slightly as a result of the formation of CO and CO bonds on the phosphor surface. CNT coating increased the atomic concentrations of O and C by 27.4% and 9%, respectively. Photoluminescence intensity decreased significantly, by 52%, when CNT concentration of 1.5wt% was coated. This is attributed to covering the phosphor with black CNTs/carbons and the formation of CO and CO bonds on the phosphor surface. Conversely, cathodoluminescence (CL) intensity was improved by a factor of 3.86 when 1.25wt% of CNTs was coated, attributing to improved conductivity, reduced charging, and increased CL excitation probability of the phosphor. The influence of CNT coating on the luminescence of LaPO4:Tm was compared with that of LaPO4:Eu phosphor. Blue CL was observed from LaPO4:Tm, it is potential for field emission lamp application.

Apparatus for temperature-dependent cathodoluminescence characterization of materials

An apparatus for characterization of temperature-dependent cathodoluminescence (CL) of solid-state materials is presented. This device excites a specimen using an electron beam and the CL emission is collected from the specimen side opposite the e-beam irradiation. The design of the temperature-controlled specimen holder that enables cooling down to 100 K and heating up to 500 K is described. The desired specimen temperature is automatically stabilized using a PID controller, which is the proportional-integral-derivative control feedback loop. Moreover, the specimen holder provides in situ e-beam current measurement during the specimen excitation. The apparatus allows the measurement of the CL intensity, the CL spectrum, or the CL intensity decay depending on the specimen temperature, or on a variety of excitation conditions, such as excitation energy, electron current (dose), or excitation duration. The apparatus abilities are demonstrated by an example of the CL measurements of the YAG:Ce single-crystal scintillator.

Red LaPO4:Eu Nanophosphor for Near UV LED and Field Emission Display Applications

For the phosphor materials, lanthanum phosphate (LaPO4) phosphor is one of potential materials for use in energy-efficient lightings, especially for ultraviolet (UV) light emitting diode (LED) and field emission display (FED) applications. In recent years, with the development of nanotechnologies, the synthesis of LaPO4 phosphor with nanosize particles is of increasing scientific and technical interest. In this study, the LaPO4:Eu nanophosphor was prepared with the coprecipitation (CP) method using different phosphate sources and anionic surfactants. The phosphor particle size analyzed by the SEM was about 0.5–1.2 μm. The phosphor synthesized by the CP method had improved crystallinity, smooth morphology, and decreased nonradiative transition, consequently, a twofold increase in luminescence intensity was obtained when compared with the phosphor prepared by the solid state reaction method. Under the excitation at wavelength of 396 nm (the emission wavelength of a UV LED), the LaPO4:Eu phosphor showed a red emission with peak at 594 nm (5 D 0 → 7 F 1). The maximum luminescence intensity of phosphor was obtained when it was doped with 7 mol% Eu3+ and sintered at 1200°C for 2 h. Emission degradation measurement shows that the emission intensity at wavelength of 594 nm was decayed with single-exponential mechanism. The measured decay time was 2.95 ms. The absorption and emission spectra of the phosphor varied with the kinds of phosphate sources. Using H3PO4 as phosphate source, a strong charge transfer band (CTB) absorption and high 5 D 0 → 7 F 2 emission were measured. When (NH4)2HPO4 and Na5P3O10 were used, a red-shifted and decreased CTB absorption was observed. This shift was caused by the increase in O2- - Eu3+ distance and the crystallinity variation of the phosphor, which led to the decrease in charge transfer energy. On the other hand, for the f-f orbital absorption transitions of Eu3+ inner electrons, the energy absorptions of phosphor prepared with phosphate sources of (NH4)2HPO4 and Na5P3O10 were stronger than that of phosphor prepared with H3PO4. Hence, an increased 5 D 0 → 7 F 1 emission was observed. The highest crystallographic symmetry of Eu3+ in the lattice and a high color-purity red emission were obtained when the (NH4)2HPO4 was used as phosphate source material. To further enhance the photoluminescence (PL) of the phosphor for LED application, anionic dispersants were used to modify the surface of phosphor particles. The dominant growth plane was changed from (200) to (120) plane when the phosphor was synthesized with dispersants. The decay time of phosphor was 3.02, and 3.15 ms when SDS and (NaPO3)6 dispersants were used, respectively. A certain improvement in the decay time was observed. Apparently, the surface states of phosphor particles were modified, hence, the PL intensity was enhanced. The optimal crystallinity and the maximum PL intensity of phosphor were obtained when 1 and 3 mol% of (NaPO3)6 and SDS were used, respectively, and the corresponding increment in the PL intensity was 10 and 7%. Moreover, conductive material of carbon nanotubes (CNTs) was doped to improve the cathodoluminescence (CL) of phosphor for FED application. The addition of CNTs reduced the accumulation of electrons on the phosphor surface. Consequently, the CL intensity was increased. The maximum CL intensity was obtained when 1 wt% of CNT was doped. The CL intensity was enhanced by 1.35 times.

Optical and structural properties of Zn1−x Mg x O ceramic materials

This paper reports structural, optical and cathodoluminescence characterizations of sintered Zn1−x Mg x O composite materials. The effects of MgO composition on these film properties have been analyzed. X-ray diffraction (XRD) confirms that all composites are polycrystalline with prominent hexagonal wurtzite structure along two preferred orientations (002) and (101) for the crystallite growth. Above doping content x = 10 %, the formation of the hexagonal ZnMgO alloy phase and the segregation of the cubic MgO phase start. From reflectance and absorption measurements, we determined the band gap energy which tends to increase from 3.287 to 3.827 eV as the doping content increases. This widening of the optical band gap is explained by the Burstein–Moss effect which causes a significant increase of electron concentration (2.89 × 1018−5.19 × 1020 cm−3). The luminescent properties of the Zn1−x Mg x O pellets are studied by cathodoluminescence (CL) at room and liquid nitrogen temperatures under different electron beam excitations. At room temperature, the CL spectra of the Zn1−x Mg x O composites exhibit a dominant broad yellow-green light band at 2.38 eV and two ultraviolet emission peaks at 3.24 and 3.45 eV corresponding to the luminescence of the hexagonal ZnO and ZnMgO structures, respectively. For the doped ZnO samples, it reveals also new red peaks at 1.72 and 1.77 eV assigned to impurities’ emissions. However, the CL spectra recorded at 77 K show the presence of excitonic emission peaks related to recombination of free exciton (X A), neutral donor-bound excitons (D0X) and their phonon replicas. The CL intensity and energy position of the green, red and ultraviolet emission peaks are found to depend strongly on the MgO doping content. The CL intensity of the UV and red emissions is more enhanced than the green light when the MgO content increases. CL imaging analysis shows that the repartition of the emitting centers in Zn1−x Mg x O composites is intimately connected to the film composition and surface morphology.

Positional-dependent luminescence property of β-SiAlON:Eu2+ phosphor particle

The relationship between the luminescence property and particle faces of the β-SiAlON:Eu2+ phosphors was investigated by performing the cathodoluminescence (CL) measurements on the tip and side faces of the rod-like phosphor particles. It was found a positional dependence of the CL intensity on the particle faces, that is, the side face possessed higher CL intensity than the tip face, probably due to uneven distribution of the Eu2+ sites in the β-SiAlON host particles: the Eu2+ ions more intensively concentrated at the side face of the particle, particularly at the central area of the side face, than at the tip face.

Defect Driven Emission from ZnO Nano Rods Synthesized by Fast Microwave Irradiation Method for Optoelectronic Applications

ABSTRACTBecause of its large direct band gap of 3.37 eV and high exciton binding energy (∼60 meV), which can lead to efficient excitonic emission at room temperature and above, ZnO nanostructures in the würtzite polymorph are an ideal choice for electronic and optoelectronic applications. Some of the important parameters in this regard are free carrier concentration, doping compensation, minority carrier lifetime, and luminescence efficiency, which are directly or indirectly related to the defects that, in turn, depend on the method of synthesis. We report the synthesis of undoped ZnO nanorods through microwave irradiation of an aqueous solution of zinc acetate dehydrate [Zn(CH3COO)2. 2H2O] and KOH, with zinc acetate dihydrate acting as both the precursor to ZnO and as a self-capping agent. Upon exposure of the solution to microwaves in a domestic oven, ZnO nanorods 1.5 µm -3 µm and 80 nm in diameter are formed in minutes. The ZnO structures have been characterised in detail by X-ray diffraction (XRD), selective area electron diffraction (SAED) and high-resolution scanning and transmission microscopy, which reveal that each nanorod is single-crystalline. Optical characteristics of the nanorods were investigated through photoluminescence (PL) and cathodoluminescence (CL). These measurements reveal that defect state-induced emission is prominent, with a broad greenish yellow emission. CL measurements made on a number of individual nanorods at different accelerating voltages for the electrons show CL intensity increases with increasing accelerating voltage. A red shift is observed in the CL spectra as the accelerating voltage is raised, implying that emission due to oxygen vacancies dominates under these conditions and that interstitial sites can be controlled with the accelerating voltage of the electron beam. Time-resolved fluorescence (TRFL) measurements yield a life time (τ) of 9.9 picoseconds, indicating that ZnO nanorods synthesized by the present process are excellent candidates for optoelectronic devices.