S.-B. Lee

Deposition of aluminum-doped zinc oxide films by RF magnetron sputtering and study of their structural, electrical and optical properties

Highly oriented undoped and aluminum-doped ZnO (AZO) films in the (002) direction were prepared by RF magnetron sputtering on glass substrates with specifically designed ZnO targets containing different amounts of Al(OH)3 powder as doping source. A systematic study of the influence of deposition parameters such as Al(OH)3 content in the target, the target–substrate distance (Dts), deposition time and substrate temperature on the structural, electrical and optical properties of the as-grown AZO films was carried out. XRD shows that AZO (002) crystal grew parallel to the substrate. With increasing Dts the growth rate increased, while the substrate temperature did not affect the growth rate. The as-grown AZO films not only have an average transmittance of >85% in the visible region, but also have an optical bandgap between 3.2 and 3.64 eV, depending on the sputtering parameters. The resistivity of the film deposited at Dts=45 mm from a 4 wt.% Al(OH)3-doped ZnO target was approximately 9.8×10−2 Ω cm, showing semiconductor properties.

Deposition of aluminum-doped zinc oxide films by RF magnetron sputtering and study of their surface characteristics

Transparent conductive, undoped and aluminum-doped ZnO (AZO) thin films were prepared on the glass substrates at deposition temperature in the range of room temperature (R.T.) ;300 8C by RF magnetron sputtering. Highly oriented AZO films in the w002x direction were obtained with specifically designed ZnO targets. A systematic study on the dependence of deposition parameters on the structural, optical and electrical properties of the as-grown AZO films was mainly investigated in this work. The AZO film prepared at R.T. with 4 wt.% Al(OH) doped a ZnO target under a target-to-substrate distance (D ) of 3 ts

Hydrogenated amorphous and crystalline SiC thin films grown by RF-PECVD and thermal MOCVD; comparative study of structural and optical properties

Thin films of hydrogenated amorphous silicon carbide (a-SiC:H) and crystalline silicon carbide (c-SiC) with different compositions were deposited on Si( 100 ) substrates by both RF plasma enhanced chemical vapor deposition and thermal metal organic chemical vapor deposition methods using a SiH qCH gas mixture and a single molecular precursor of diethylmethylsilane, 44 respectively. In this experiment, we mainly investigated the dependence of structural and optical properties of a-SiC:H and c-SiC thin films on the deposition parameters such as deposition temperature, pressure, RF power and annealing temperature. From this comparative study on structural and compositional differences of the a-SiC:H and c-SiC thin films, we realized that there are much different hydrogen contents and crystallinity in the films depending on the deposition temperature and annealing temperature. With increasing these parameters, moreover, the hydrogen contents and crystallinity are drastically changed to be less hydrogen and better crystalline films starting from amorphous, polycrystalline and single crystalline, sequentially. In addition, their optical properties are also strongly changed, for example, the refractive index and optical band gap are increased with increasing deposition temperature, pressure, RF power and annealing temperature. And the structural and optical properties of c-SiC thin film were analyzed with X-ray diffraction, scanning electron microscope, and infrared absorption techniques. 2003 Elsevier Science B.V. All rights reserved.

Growth of β-SiC nanowires and thin films by metalorganic chemical vapor deposition using dichloromethylvinylsilane

We deposited β-SiC thin films and β-SiC nanowires by metalorganic chemical vapor deposition (MOCVD) on bare Si(100) and Ni-coated Si(100) substrates using dichloromethylvinylsilane [CH2CHSi(CH3)Cl2] as a single molecular precursor. Deposition pressures and temperatures were about 50 mTorr and 800–1200 °C, respectively, and deposition durations were 0.5–2 h. Nickel plays an important role as a catalyst in growing β-SiC nanowires. As-deposited zinc-blende SiC thin films and nanowires were grown separately. Initial growth rates are strongly dependent on deposition temperature. TEM analysis showed that the as-deposited β-SiC nanowires are wrapped with very thin amorphous carbon layers, have a [111] growth direction with well-crystallized structure, and modulated diameters. XPS and EDX analyses show that the Si:C compositions are about 1.0:1.2, suggesting possible applications to both field emitters and electronic devices.

Deposition of silicon carbide films using a high vacuum metalorganic chemical vapor deposition method with a single source precursor: Study of their structural properties

Silicon carbide (SiC) thin films were prepared on Si(100) substrates by high vacuum metalorganic chemical vapor deposition using a single-source precursor at various growth temperatures in the range of 700–1000 °C. The precursor is diethylmethylsilane, and is used without carrier gas. The effects of substrate temperature as well as deposition time on the crystal growth were investigated. The optimum temperature for the formation of high quality polycrystalline SiC thin films was found to be 900 °C on the basis of x-ray diffraction and transmission electron diffraction results. X-ray photoemission spectroscopy shows that SiC films grown at 900 °C have slightly carbon-rich compositions (Si:C=1:1.2) in the surface region, but stoichiometric composition in the bulk. Scanning and transmission electron microscope images show the influence of substrate temperature on the grain size and crystallinity of the films. Large grain sizes and high quality crystallinity can be obtained below 900 °C.

Impedance Spectroscopic Study of p-i-n Type a-Si Solar Cell by Doping Variation of p-Type Layer

We investigated p-i-n type amorphous silicon (a-Si) solar cell where the diborane flow rate of the p-type layer was varied and the solar cell was measured static/dynamic characteristics. The p/i interface of the thin film amorphous silicon solar cells was studied in terms of the coordination number of boron atoms in the p layer. p-type layer and p/i interface properties were obtained from the X-ray photoelectron spectroscopy (XPS) and impedance spectroscopy. One of the solar cells shows open circuit voltage (𝑉oc)=880 mV, short circuit current density (𝐽sc)=14.21 mA/cm2, fill factor (FF)=72.03%, and efficiency (𝜂)=8.8% while the p-type layer was doped with 0.1%. The impedance spectroscopic measurement showed that the diode ideality factor and built-in potential changed with change in diborane flow rate.

Synthesis of a material for semiconductor applications: Boron oxynitride prepared by low frequency rf plasma-assisted metalorganic chemical vapor deposition

We have synthesized a material, boron oxynitride (BON), deposited as films on Si(100) substrates by low frequency rf-derived plasma-assisted metalorganic chemical vapor deposition (MOCVD), and have studied the electrical and optical properties of these films. The effects of growth conditions such as the flux of the feed gas and growth time on these properties are investigated. Our data show that the electrical resistance decreases with an increase in nitrogen flux and growth time. Amorphous BON thin films grown at relatively low temperatures have higher resistance than microcrystal-containing films deposited at high temperature. Thus by controlling the nitrogen content of the film we can make BON thin films that are either semiconducting or insulating. We also monitored optical emission spectra (OES) during MOMCVD to analyze reaction of the gas phase in the plasma. Based on the OES result we confirm that BON thin films can be prepared under a nitrogen plasma.

Growth of cubic SiC thin films on Si(001) by high vacuum chemical vapor deposition using 1,3-disilabutane and an investigation of the effect of deposition pressure

We have deposited cubic SiC thin films on Si(001) substrates by high vacuum chemical vapor deposition (CVD) using a single molecular precursor of 1,3-disilabutane (DSB) at various temperatures (600–1000 °C) and pressures in the range of 1×10−6–1×10−5 Torr. A single-crystalline cubic SiC thin film with stoichiometric composition can be obtained under deposition conditions of 900–1000 °C and 4.0–6.5×10−6 Torr. However, on increasing the deposition pressure and decreasing the growth temperature to 1×10−5 Torr and 600 °C, respectively, the film became polycrystalline. The effect of deposition pressure on the film growth rate and crystallinity was also studied. Based on the experimental results from x-ray diffraction, x-ray photoelectron spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy, and transmission electron diffraction, the best SiC film was grown at 900 °C and 6.5×10−6 Torr of DSB at a maximum growth rate of 0.1 μm/h. The thicknesses of as-grown films were determined by ...

Synthesis and characterization of BON thin films using low frequency RF plasma enhanced MOCVD: effect of deposition parameters on film hardness

With the expectation of getting hard material, we have firstly grown the BON thin film by radio frequency plasma enhanced metal-organic chemical vapor deposition with 100 kHz frequency and trimethyl borate precursor. The plasma source gases used in this study were Ar and H , and two kinds of nitrogen source gases, N and NH , were also employed. The as-grown films 22 3 were characterized with XPS, IR, SEM and Knoop microhardness tester. The film growth rate was influenced both by substrate temperature and by nitrogen source gas. It decreased with increasing the substrate temperature, and was higher by using NH 3 rather than by N . The hardness of the film was dependent on several factors such as nitrogen source gas, substrate temperature 2 and film thickness due to the variation of the composition and the structure of the film. Both nitrogen and carbon-content could raise the film hardness, on which nitrogen content had stronger effect than carbon. The smooth morphology and continuous structure yielded high hardness. The maximum hardness of BON film was approximately 10 GPa. 2003 Elsevier Science B.V. All rights reserved.

Study on the characteristics of toluene-tetraethoxysilane hybrid plasma-polymer thin films

This study investigated the interaction of varied plasma power with ultralow-k toluene-tetraethoxysilane (TEOS) hybrid plasma-polymer thin films, as well as changing electrical and mechanical properties with varied radio frequency (rf 13.56MHz) power of plasma. The hybrid films with low dielectric constants were deposited on silicon(100) substrates by plasma enhanced chemical vapor deposition system. Toluene and tetraethoxysilane were utilized as organic and inorganic precursors. In addition, bubbling ratio of TEOS to toluene is 1:10. The as-grown hybrid plasma-polymer thin films were characterized by Fourier transform infrared spectroscopy, atomic force microscopy (AFM), nanoindentation, I-V curves, and capacitance. To analyze their trends of electrical and mechanical properties, the thin films were grown under conditions of various rf powers. The IR spectra showed them to have completely different chemical functionalities from the liquid toluene and TEOS precursors. The AFM images showed changing of sur...