Plasma-enhanced Metalorganic Chemical Vapor Deposition Research Articles

Low temperature epitaxial technology for GaN-based materials

<p indent="0mm">The band gap of GaN-based semiconductor materials covers the entire visible light band and has excellent physical and chemical properties, which makes it widely used in the fabrication of optoelectronic devices, power electronic devices, and radio frequency and microwave devices. Traditional GaN-based materials are usually epitaxially grown on high-temperature-resistant single-crystalline substrates such as sapphire, silicon, or silicon carbide using metal-organic chemical vapor deposition (MOCVD), molecular beam epitaxy (MBE), or hydride vapor phase epitaxy (HVPE). These epitaxial techniques usually use high temperature to crack the precursors involved in the reaction. With the deepening of informatization and intelligentization, the common demands for low-cost and flexibility of opto(electronic) devices have emerged. On one hand, the display technology is a key link to realize information exchange and intelligence. Moving towards an intelligent society requires further reduction of the display cost per unit area. At the same time, the wearable and portable flexible display technology also has broad application prospects. In addition, solid-state lighting has gradually penetrated into every corner of human life with the improvement of device performance. The application scenarios are rich and colorful. Judging from this, low-cost surface light sources will be a strong competitor for the next generation of lighting technology routes. On the other hand, reducing the fabrication cost of electronic devices per unit area also needs more attention in the future. For example, flexible electronic skin has broad and huge application prospects in artificial limbs, robotics, medical detection and diagnosis, etc., which has also spawned the demand for low-cost flexible sensors. It can be seen that the common requirements of the above applications for core components are low cost and flexibility, which is also one of the main development directions of the next generation of (opto)electronic devices. Amorphous substrates (such as glass, plastic, metal, polyethylene terephthalate (PET), polydimethylsiloxane (PDMS), etc.) that are cheap and easy to fabricate are ideal choices, but a significant disadvantage is that amorphous substrates cannot withstand high growth temperatures. Therefore, the need for low-temperature epitaxy of GaN-based materials has arisen, that is, a kind of epitaxy equipment that can use external electric field energy to crack the reaction precursor at low temperatures. So far, a variety of low-temperature epitaxial technologies have been developed based on the physical vapor deposition (PVD) and the chemical vapor deposition (CVD), and preliminary research results have been obtained. The PVD techniques include reactive magnetron sputtering, plasma-assisted MBE (PA-MBE), pulsed laser deposition (PLD), pulsed sputtering deposition (PSD), laser MBE (LMBE), etc. The CVD techniques include remote plasma CVD (RPCVD), migration enhanced afterglow CVD (MEA-CVD), remote plasma-enhanced MOCVD (RPEMOCVD), radical-enhanced MOCVD (REMOCVD), electron cyclotron resonance plasma-enhanced MOCVD (ECR-PEMOCVD), inductive coupled plasma MOCVD (ICP-MOCVD), etc. In this paper, the two types of low-temperature epitaxial technologies are introduced in detail, including the device structure, working conditions and related epitaxial growth results, and the characteristics of each type of technology are summarized. Finally, the development prospect of low temperature epitaxial technologies is prospected, and the focus of future research is pointed out. We hope this work can provide a useful reference for the low temperature epitaxy research of GaN-based materials.

Using Modified-Intake Plasma-Enhanced Metal-Organic Chemical Vapor Deposition System to Grow Gallium Doped Zinc Oxide.

We have used a modified-intake plasma-enhanced metal–organic chemical vapor deposition (MIPEMOCVD) system to fabricate gallium-doped zinc oxide (GZO) thin films with varied Ga content. The MIPEMOCVD system contains a modified intake system of a mixed tank and a spraying terminal to deliver the metal–organic (MO) precursors and a radio-frequency (RF) system parallel to the substrate normal, which can achieve a uniform distribution of organic precursors in the reaction chamber and reduce the bombardment damage. We examined the substitute and interstitial mechanisms of Ga atoms in zinc oxide (ZnO) matrix in MIPEMOCVD-grown GZO thin films through crystalline analyses and Hall measurements. The optimal Ga content of MIPEMOCVD-grown GZO thin film is 3.01 at%, which shows the highest conductivity and transmittance. Finally, the optimal MIPEMOCVD-grown GZO thin film was applied to n-ZnO/p-GaN LED as a window layer. As compared with the indium–tin–oxide (ITO) window layer, the n-ZnO/p-GaN LED with the MIPEMOCVD-grown GZO window layer of the rougher surface and higher transmittance at near UV range exhibits an enhanced light output power owing to the improved light extraction efficiency (LEE).

Study on Preparation and Properties of InN Films on Self-Supporting Diamond Substrates Under Different Nitrogen Flows

Several InN film samples with superb properties were prepared on a self-supporting diamond substrate for different nitrogen flow rates using an electron cyclotron resonance plasma-enhanced metal-organic chemical vapor deposition (ECR-PEMOCVD) system. After the InN film samples were obtained, the samples were characterized via reflected high-energy electron diffraction (RHEED), X-ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscope (AFM), and electron probe micro-analysis (EPMA) to study the effect of the nitrogen flow on the quality of the InN films. The experimental results show that the variation in the nitrogen flow has a great impact on the preferential growth of the (0002) crystal plane of the InN thin-film. By increasing the nitrogen flow moderately, the crystal quality of the film is improved. Under the growth condition of appropriate nitrogen flow, InN thin-films with a preferred orientation along the c-axis can be obtained, and the surface of the resulting InN thin-films is relatively flat. However, a high nitrogen flow does not improve the film crystal quality. The results of the experiment and of the analysis show that the InN films prepared with a nitrogen flow rate of 80 sccm have an excellent preferential orientation. The result of the EPMA test shows that the percentages of the In and N atoms in the prepared film samples are close to a ratio of 1:1, and a small amount of metal In droplets is present. In addition, the InN thin-films prepared in such condition have an excellent surface morphology and composition.

Growth of high-quality near-ultraviolet light-emitting diodes used InGaN/GaN multiple quantum wells

High-quality near-ultraviolet (UV) light-emitting diodes (LEDs) used InGaN/GaN multiple quantum wells (MQWs) have been grown on ScMgAlO4 substrates by plasma enhanced metalorganic chemical vapor deposition (PEMOCVD). The structural properties and optoelectronic properties of InGaN/GaN MQWs are characterized carefully. The full-width at half-maximums (FWHMs) for GaN(0002) and GaN(10–12) X-ray rocking curves are 180 and 190 arcsec, respectively, indicating high crystalline quality of GaN epitaxial films. The as-grown InGaN/GaN MQWs with sharp and abrupt hetero-interfaces have been also obtained and confirmed by high-resolution X-ray diffraction and high-resolution transmission electron microscopy measurements. Meanwhile, there is a photoluminescence peak at 385 nm with an FWHM of 23.2 nm at 300 K and the internal quantum efficiency (IQE) for these InGaN/GaN MQWs is measured to be as high as 79.8%, revealing the high optoelectronic properties. This work sheds light on the preparation of high-performance near-UV LEDs for the application of UV curing, lighting, etc.

Applications of plasma-enhanced metalorganic chemical vapor deposition

Abstract The use of plasma enhancement for growth of III-V compound semiconductor materials by metalorganic chemical vapor deposition (MOCVD) is examined, to improve control of microstructure, develop understanding of the underlying growth mechanisms, and expand the range of materials combinations for photovoltaic and solid-state lighting applications. Whereas plasma is commonly used with group-IV materials, such as silicon, few studies have examined the impact of plasma-enhanced MOCVD (PE-MOCVD) for III-V materials growth. PE-MOCVD provides improved decomposition of metalorganic precursors, which is driven by hydrogen plasma to augment hydride reactions and thermal pyrolysis, but plasma generation requires low reactor pressure. We have demonstrated elemental Al films grown by PE-MOCVD, which show distinct crystallographic texturing, and assume epitaxial microstructure upon post-growth annealing. We also demonstrate PE-MOCVD of GaAs at temperatures as low as 300 °C. With increasing radio-frequency power, the GaAs growth rate shows a transition from power limited to mass-transport limited. PE-MOCVD grown Ga0.5In0.5P shows no detectable spontaneous atomic ordering, which offers a mechanism to form order/disorder unicompositional heterostructures, without temperature change or impurity incorporation. In its current implementation, PE-MOCVD grown films have shown microstructural degradation, that we attribute to direct plasma exposure during growth. Improvements in the system design and growth sequences are at the focus of on-going efforts.

Optimization of a TiN PE-MOCVD Process Using DoE Methodology

The miniaturization of circuits is advancing. During chip manufacturing, structures are filled for example by plasma enhanced metal organic chemical vapor deposition (PE-MOCVD). This process reaches its limits in case of very high aspect ratios. However, it is an unsolved question to what extent PE-MOCVD can achieve results with an modified process using Design of Experiment (DoE) methodology. In this context, this work addresses the characterization of a PE-MOCVD of titanium nitride (TiN). Based on the current state of the art, selected responses and factors are considered of the plasma treatment step. The derived process for unstructured wafers is feasible for the stress or for the resistivity. A uniform filling inside a structure with high aspect ratio include for a process temperature of 400°C increase in number of cycles, plasma power, plasma gas ratio hydrogen to nitrogen and plasma treatment time. At lower process temperatures and a significantly increased number of cycles a structure filling is achieved with much less titanium nitride. In contrast to the current process configuration, the deposited titanium nitride film is more uniform inside the entire test structure. Consequently, this paper provides approaches to use the PE-MOCVD for structures with increasing aspect ratios.

Plasma deposited novel nanocatalysts for CO2 hydrogenation to methane

The catalytic hydrogenation of CO2 to methane has been receiving an increasing attention as a method to mitigate the concentration of CO2 in the atmosphere through the production of synthetic natural gas. Finding the effective catalyst is the key factor to make this process feasible. In the present work, hydrogenation of CO2 into CH4 over novel metal oxide nanocatalysts supported on wire gauzes made from kanthal steel (FeCrAl) has been studied. The series of thin films of active phase were prepared by plasma-enhanced metalorganic chemical vapor deposition (PEMOCVD), containing cobalt spinel (Co3O4), ruthenium oxide (RuO2), mixed oxides (RuO2/Co3O4) and iron oxide (Fe2O3). The activity of the prepared nanocatalysts was tested in the gradientless reactor in the temperature range of 150–500°C. The RuO2 catalyst revealed the highest both the yield of methane and the reaction rate, while the Fe2O3 catalyst promoted the CO production through reverse water-gas shift reaction. The results of the present studies are the foundation for further research on a new class of nanomaterials with high catalytic properties for the methanation reaction.

Cobalt oxide-based catalysts deposited by cold plasma for proton exchange membrane fuel cells

In proton exchange membrane fuel cells (PEMFC), both the anodic hydrogen oxidation reaction and the cathodic oxygen reduction reaction (ORR) require appropriate catalysts. So far, platinum-based catalysts are still the best option for this purpose. However, because these catalysts are too expensive for making commercially viable fuel cells, extensive research over the past decade has focused on developing noble metal-free alternative catalysts. In this paper, an approach based on cobalt oxide films fabricated by plasma-enhanced metal-organic chemical vapor deposition is presented. Such a material can be used to prepare catalysts for ORR in PEMFC. The films containing CoOX were deposited on a carbon paper thereby forming the electrode. Morphology and atomic composition of the films were investigated by scanning electron microscopy and energy-dispersive X-ray spectroscopy, respectively. The possibility of their application as the electro-catalyst for ORR in PEMFC was investigated and the electro-catalytic activities were evaluated by the electrochemical measurements and single cell tests. It was found that the fuel cell with Pt as the anode catalyst and CoOX deposit as the cathode catalyst was characterized by the open circuit voltage of 635mV, Tafel slope of approx. 130mV/dec and the maximum power density of 5.3W/m2.

Deposition of Iridium Thin Films on Three‐Dimensional Structures With PE‐MOCVD

Iridium thin films are deposited on sub‐micrometer three‐dimensional trench structures by plasma‐enhanced metal‐organic chemical vapor deposition (PE‐MOCVD). The iridium precursor used in this study is (ethylcyclopentadienyl)(1,5‐cyclooctadiene)iridium [Ir (EtCp)(1,5‐COD)]. Various process conditions at substrate temperatures from 300 °C to 450 °C, with and without plasma enhancement, are investigated and compared. Crystal structure of the deposited iridium films is analyzed by X‐ray diffraction (XRD). Step coverage of the deposited iridium films on three‐dimensional trench structures is analyzed by scanning electron microscopy (SEM). Surface morphology is quantitatively evaluated by atomic force microscopy (AFM) and the electrical resistivity of the deposited Ir films is measured by the four‐point probe method.

Plasma Deposition and Characterization of Copper-doped Cobalt Oxide Nanocatalysts

A series of pure and copper-doped cobalt oxide films was prepared by plasma-enhanced metalorganic chemical vapor deposition (PEMOCVD). The effect of Cu-doping on the chemical structure and morphology of the deposited films was investigated. Raman and FTIR spectroscopies were used to characterize the chemical structure and morphology of the produced films. The bulk composition and homogeneity of the samples were investigated by energy dispersive X-ray microanalysis (EDX), and X-ray photoelectron spectroscopy (XPS) was employed to assess the surface chemical composition of pure and doped materials. The obtained results permit to affirm that the PEMOCVD technique is a simple, versatile and efficient method for providing homogeneous layers of cobalt oxides with a different content of copper. It has been found that pure cobalt oxide films mainly contain Co 3 O 4 in the form of nanoclusters whereas the films doped with Cu are much more complex, and CoO x (also Co 3 O 4 ), mixed Co-Cu oxides and CuO x nanoclusters are detected in them. Preliminary catalytical tests show that Cu-doped cobalt oxide films allow to initiate catalytic combustion of n-hexane at a lower temperature compared to the pure cobalt oxide (Co 3 O 4 ) films. From what has been stated above, the plasma-deposited thin films of Cu-doped cobalt oxides pave the way towards a new class of nanomaterials with interesting catalytic properties. DOI: http://dx.doi.org/10.5755/j01.ms.19.3.2320

Catkin liked nano-Co3O4 catalyst built-in organic microreactor by PEMOCVD method for trace CO oxidation at room temperature

In this paper, tricobalt tetraoxide (Co3O4) catalyst was coated on the polydimethylsiloxane microchannel by the plasma-enhanced metal-organic chemical vapor deposition technology. The obtained Co3O4 film was characterized by SEM, XRD, XPS, and TEM, and the results show that the as-deposited Co3O4 film was initially composed of many cauliflowers-shaped microclusters. Also, the microcauliflower was transformed from an amorphous phase to a crystal phase when the Co3O4 film was treated by Ar and O2 plasma for more than 20 min, and the crystal lattice line occurred on the surface of nano-sized-Co3O4 particles. Meanwhile, the interface of Co3O4 particles with diameter between 3 and 12 nm became obvious and some nano-catkin structures were also formed on the Co3O4 film. The ratio of Co3+/Co2+ in the spinel-type Co3O4 was nearly 2, and the nano-particles predominantly expose their {311}, {111}, and {220} planes. These morphologies and structure characteristics were found to be ideal for increasing the catalytic activity efficiency of Co3O4 for CO oxidation, and the catalytic stability of Co3O4 coated on the organic microreactor lasted nearly 85 h for trace CO oxidation at room temperature.

The different structure characteristics of nanosized Co3O4 film crystallized by the annealing and plasma techniques

In this study, we deposited nano-Co3O4 film on silicon substrate using plasma-enhanced metal—organic chemical vapor deposition (PEMOCVD), and the structure difference of Co3O4 crystallized by the annealing and the Ar/O2 plasma techniques were explored by SEM, TEM, XRD, and XPS. Compared to the net morphology of Co3O4 film treated with high calcinations temperature, the cauliflowers-shaped micro-clusters were changed to nano-catkin when the sample was treated with Ar and O2 plasma for 40min. Additionally, both samples (annealed and plasma-treated) showed the formation of both the {311} and {220} planes. The surface richness of active Co3+ sites on the exposed {220} plane indicated that the as-deposited nano-Co3O4 films have potential catalytic properties for CO and hydrocarbon oxidation.

Production of photocatalytically active titania layers: A comparison of plasma processes and coating properties

The deposition of photocatalytically active titania layers at ambient temperature was developed using the reactive dc magnetron sputtering (PVD) and the plasma enhanced metal organic chemical vapour deposition (PE-MOCVD) method at reduced and at atmospheric pressure. An increase of the photo-activity in the near ultraviolet and blue light irradiation was achieved by doping the titania layers using the elements nitrogen and/or carbon.Investigation of the chemical and structural features of the titania layers produced at similar experimental conditions was carried out by X-ray photoelectron spectroscopy, atomic force microscopy, FTIR, and Raman. The optical energy bandgap and photocatalytic activity at 365/428nm for various titania layers were analysed using ellipsometry and the methylene blue dye bleaching according to ISO 10678:2010, respectively. The reduction of the aqueous methylene blue solution was similar for the two categories of titania layers. However, the photo-induced properties such as the mineralization of stearic acid for investigating anti-fingerprint effects evidenced a weaker interaction between the hydrophobic PE-MOCVD titania surfaces than for the hydrophilic and rougher PVD produced titania layers when irradiated under ultraviolet.The observed differences were related to the chemical and structural features since the hydrophobic PE-MOCVD produced titania layers were mostly amorphous and nitrogen/carbon incorporation into TiO2 led to an enhanced photocatalytic ability by a factor of two regarding the dye tests, whereas the energy bandgap remained at about 3.2eV. However, the energy bandgap was red-shifted by doping the hydrophilic and partly crystalline PVD titania layers, but decremented the anatase domains and reduced the wettability of the surface. Substitutional and interstitial doping of nitrogen and carbon was evidenced by XPS and an additional benefit regarding the adhesion and abrasion resistance was observed for the tailored doping of titania layers.

Characterization of Palladium-based Thin Films Prepared by Plasma-enhanced Metalorganic Chemical Vapor Deposition

The plasma-enhanced metalorganic chemical vapor deposition (PEMOCVD) was used to prepare palladium–based thin films starting with palladium (II) acetylacetonate precursor (Pd(acac)2) mixed with argon (carrier gas). To characterize chemical structure and morphology of deposited films Raman spectroscopy and electron diffraction techniques were used. The energy dispersive X-ray microanalysis (EDX) was applied to specify composition of films. The film thickness was estimated by ellipsometric measurements. The obtained results show that the films have various composition depending on deposition parameters. It has been found that the thermal decomposition at 623 K of the films leads to the formation of fine 5 nm – 10 nm size palladium nanoparticles, to which the catalytic activity is attributed.DOI: http://dx.doi.org/10.5755/j01.ms.18.2.1913

Zinc oxide (ZnO) grown on flexible substrate using dual-plasma-enhanced metalorganic vapor deposition (DPEMOCVD)

This study investigates the temperature dependence of zinc oxide (ZnO) grown on polyestersulfone (PES) flexible substrates using the dual plasma-enhanced metal–organic chemical vapor deposition (DPEMOCVD) system. The proposed method uses a direct voltage (DC) and radio-frequency (RF) plasma system. The group-VI precursor, oxygen (O2), can be completely ionized by the DC plasma system. The effect of optimal DC plasma power on ZnO thin films is thoroughly investigated using X-ray diffraction (XRD). The experimental results indicate that the crystalline structure and optical and electrical properties of ZnO thin films grown on PES substrates are dependent on the deposition temperature. The optimum deposition temperature for ZnO thin films deposited on PES substrates is 185°C, whereas the DC and RF plasma power is 1.8W and 350W, respectively. Additionally, the wettability characteristic regarding the UV irradiation time was assessed by measuring the water contact angle. Under the UV irradiation for 60min, the ZnO film grown at 185°C represents a low contact angle of 5°, which approaches to a superhydrophilic surface.

Photocatalytically Active Titania Produced by MOCVD Plasma Process

The deposition of photocatalytically active titania layers at ambient temperature was developed using the plasma enhanced metal organic chemical vapour deposition (PE-MOCVD) method at low and atmospheric pressure. An increase of the photo-activity in the near ultraviolet (UV) and blue light irradiation was achieved by doping the titania layers using the elements nitrogen and/or carbon. Investigation of the chemical and structural features of the titania layers was carried out by x-ray photoelectron spectroscopy, atomic force microscopy, and Raman. The optical energy bandgap and photocatalytic activity at 365/428 nm for various titania layers were analyzed using ellipsometry and the methylene blue dye bleaching according to ISO 10678:2010, respectively. The reduction of the aqueous methylene blue solution was similar for the two categories of titania layers. However, the photo-induced properties such as the mineralization of stearic acid for investigating anti-fingerprint effects evidenced a weaker interaction between the mostly hydrophobic PE-MOCVD titania surfaces than for the hydrophilic and rougher PVD produced titania layers when irradiated under UV light. The observed differences were related to the chemical and structural features since the hydrophobic PE-MOCVD produced titania layers were amorphous and nitrogen and carbon incorporation into TiO2 led to an enhanced photocatalytic ability by a factor of two regarding the dye tests, whereas the energy bandgap remained at about 3.2 eV. Substitutional and interstitial doping of nitrogen and/or carbon was evidenced by XPS. An additional benefit regarding the adhesion and abrasion resistance was observed for the tailored doping of titania layers.

Lipon thin films grown by plasma-enhanced metalorganic chemical vapor deposition in a N 2–H 2–Ar gas mixture

Lithium phosphorus oxynitride (Lipon) thin films have been deposited by a plasma-enhanced metalorganic chemical vapor deposition method. Lipon thin films were deposited on approximately 0.2 μm thick Au-coated alumina substrates in a N 2–H 2–Ar plasma at 13.56 MHz, a power of 150 W, and at 180 °C using triethyl phosphate [(CH 2CH 3) 3PO 4] and lithium tert-butoxide [(LiOC(CH 3) 3] precursors. Lipon growth rates ranged from 10 to 42 nm/min and thicknesses varied from 1 to 2.5 μm. X-ray powder diffraction showed that the films were amorphous, and X-ray photoelectron spectroscopy (XPS) revealed approximately 4 at.% N in the films. The ionic conductivity of Lipon was measured by electrochemical impedance spectroscopy to be approximately 1.02 μS/cm, which is consistent with the ionic conductivity of Lipon deposited by radio frequency magnetron sputtering of Li 3PO 4 targets in either mixed Ar–N 2 or pure N 2 atmosphere. Attempts to deposit Lipon in a N 2–O 2–Ar plasma resulted in the growth of Li 3PO 4 thin films. The XPS analysis shows no C and N atom peaks. Due to the high impedance of these films, reliable conductivity measurements could not be obtained for films grown in N 2–O 2–Ar plasma.

Plasma-Enhanced Metalorganic Chemical Vapor deposition of Lipon Thin Films

ABSTRACTLithium phosphorus oxynitride (Lipon) thin films have been deposited by a plasmaenhanced metalorganic chemical vapor deposition (PE-MOCVD) method using triethyl phosphate [(CH2CH3)3PO4] and lithium tert-butoxide [(LiOC(CH3)3] precursors. Growth rates were between 100 and 415 Å/min, and thicknesses ranged from 1 to 2.5 μm. X-ray powder diffraction showed that the films were amorphous, and X-ray photoelectron spectroscopy revealed approximately 6.9 at.% carbon in the films. The ionic conductivity of Lipon was measured using electrochemical impedance spectroscopy (EIS) and approximately 1.02 μS/cm was obtained, which is consistent with the ionic conductivity of Lipon deposited by radio frequency magnetron sputtering of Li3PO4 targets. An all-solid-state thin-film lithium microbattery such as Li/Lipon/LiCoO2/Au/substrate was successfully fabricated with Lipon deposited by PE-MOCVD. The battery has a capacity of ca. 22 μAh/cm2μm.

Biotinylation of ZnO Nanoparticles and Thin Films: A Two-Step Surface Functionalization Study

This study reports ZnO nanoparticles and thin film surface modification using a two-step functionalization strategy. A small silane molecule was used to build up a stabilizing layer and for conjugation of biotin (vitamin B7), as a specific tag. Biotin was chosen because it is a well-studied bioactive molecule with high affinity for avidin. ZnO nanoparticles were synthesized by electrochemical deposition under oxidizing condition, and ZnO films were prepared by plasma-enhanced metal-organic chemical vapor deposition. Both ZnO nanoparticles and ZnO thin films were surface modified by forming a (3-mercaptopropyl)trimethoxysilane (MPTS) layer followed by attachment of a biotin derivate. Iodoacetyl-PEG2-biotin molecule was coupled to the thiol unit in MPTS through a substitution reaction. Powder X-ray diffraction, transmission electron microscopy, X-ray photoemission electron microscopy, atomic force microscopy, X-ray photoelectron spectroscopy, and near-edge X-ray absorption fine structure spectroscopy were used to investigate the as-synthesized and functionalized ZnO materials. The measurements showed highly crystalline materials in both cases with a ZnO nanoparticle diameter of about 5 nm and a grain size of about 45 nm for the as-grown ZnO thin films. The surface modification process resulted in coupling of silanes and biotin to both the ZnO nanoparticles and ZnO thin films. The two-step functionalization strategy has a high potential for specific targeting in bioimaging probes and for recognition studies in biosensing applications.

Light-Emitting Diode Based on ZnO by Plasma-Enhanced Metal–Organic Chemical Vapor Deposition Employing Microwave Excited Plasma

In this paper we describe the growth of nitrogen doped zinc oxide (ZnO) films on single crystal ZnO substrates by plasma-enhanced metal–organic chemical vapor deposition (PE-MOCVD) employing microwave excited high-density plasma. We used Dimethylzinc (DMZ) as a Zinc precursor, and six different types of oxygen and nitrogen precursors: O2+N2, NO, N2O, O2+NH3, NO2, and O2. This paper considers the effects of nitrogen precursor material and utilizing the plasma on the structural properties and the nitrogen concentration by atomic force microscope and secondary ion mass spectrometry. It was only when using plasma and NO2 that the nitrogen (N) doped ZnO film with the steps and terraces surface structure of two-dimensional growth could be formed by our growth method. Furthermore, we fabricated a homostructural LED comprising the N-doped ZnO film and n-type ZnO substrate, and we achieved electroluminescence (EL) in forward bias at room-temperature (RT) and the current–voltage rectifying characteristics.