http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
Transparent conductive graphene electrode in GaN-based ultra-violet light emitting diodes
Kim, Byung-Jae,Mastro, Michael A.,Hite, Jennifer,Eddy, Charles R.,Kim, Jihyun The Optical Society 2010 Optics express Vol.18 No.22
<P>We report a graphene-based transparent conductive electrode for use in ultraviolet (UV) GaN light emitting diodes (LEDs). A few-layer graphene (FLG) layer was mechanically deposited. UV light at a peak wavelength of 368 nm was successfully emitted by the FLG layer as transparent contact to p-GaN. The emission of UV light through the thin graphene layer was brighter than through the thick graphene layer. The thickness of the graphene layer was characterized by micro-Raman spectroscopy. Our results indicate that this novel graphene-based transparent conductive electrode holds great promise for use in UV optoelectronics for which conventional ITO is less transparent than graphene.</P>
Michael A. Mastro,김병재,정영훈,Jennifer K. Hite,Charles R. Eddy Jr.,김지현 한국물리학회 2011 Current Applied Physics Vol.11 No.3
Gallium nitride light emitting diodes were deposited on a sapphire substrate that was pre-patterned with an ordered two-dimensional structure. The size and arrangement of the substrate surface pattern was designed to increase the diffraction and extraction of light from the device as well as define the grain size and thus dislocation density of the GaN crystal. A close-packing of self-assembled SiO_2 nanospheres was used as the sacrificial etch mask. The etch process transferred a two-dimensional pattern into the sapphire substrate with a peak-to-peak dimension of approximately 250 nm. The distance was selected to match the emission wavelength in the crystal for optimal light scattering. Additionally, the dimensions of the crystal artificially defined the grain size of the GaN in contrast to the kinetically controlled grain size in a standard GaN on sapphire growth process.
Nanostructured n-ZnO / thin film p-silicon heterojunction light-emitting diodes.
Ahn, Jaehui,Park, Hyunik,Mastro, Michael A,Hite, Jennifer K,Eddy, Charles R,Kim, Jihyun Optical Society of America 2011 Optics express Vol.19 No.27
<P>Electroluminescence (EL) was obtained from a p-Si (100) thin film/nanostructured n-ZnO heterojunction diode fabricated by a simple dielectrophoresis (DEP) method. The Si substrate was pre-patterned with electrodes and an insulating separation layer by a standard photolithographic process. ZnO nanostructures were formed by a simple solution chemistry and subsequently transferred to the pre-patterned substrate. Application of the DEP force at a frequency of 100 kHz and 6 V peak-to-peak voltage allowed precise positioning of the ZnO nanostructures at the edge of the metal electrodes. The physically formed p-Si (100) thin film/nanostructured n-ZnO heterojunction displayed multi-color emission from the ZnO near band edge as well as emission from defective states within the ZnO band gap.</P>
Single n-GaN microwire/p-Silicon thin film heterojunction light-emitting diode.
Ahn, Jaehui,Mastro, Michael A,Klein, Paul B,Hite, Jennifer K,Feigelson, Boris,Eddy, Charles R,Kim, Jihyun Optical Society of America 2011 Optics express Vol.19 No.22
<P>The emission and waveguiding properties of individual GaN microwires as well as devices based on an n-GaN microwire/p-Si (100) junction were studied for relevance in optoelectronics and optical circuits. Pulsed photoluminescence of the GaN microwire excited in the transverse or longitudinal direction demonstrated gain. These n-type GaN microwires were positioned mechanically or by dielectrophoretic force onto pre-patterned electrodes on a p-type Si (100) substrate. Electroluminescence from this p-n point junction was characteristic of a heterostructure light-emitting diode. Additionally, waveguiding was observed along the length of the microwire for light originating from photoluminescence as well as from electroluminescence generated at the p-n junction.</P>
Jung, Younghun,Baik, Kwang Hyeon,Mastro, Michael A.,Hite, Jennifer K.,Eddy, Charles R.,Kim, Jihyun The Royal Society of Chemistry 2014 Physical Chemistry Chemical Physics Vol.16 No.30
<P>Wet chemical etching using hot KOH and H<SUB>3</SUB>PO<SUB>4</SUB> solutions was performed on semipolar (112&cmb.macr;2) and nonpolar (112&cmb.macr;0) GaN films grown on sapphire substrates. An alternating KOH/H<SUB>3</SUB>PO<SUB>4</SUB>/KOH etch process was developed to control the orientation of the facets on the thin-film surface. The initial etch step in KOH produced <I>c</I>- and <I>m</I>-plane facets on the surface of both semipolar (112&cmb.macr;2) and nonpolar (112&cmb.macr;0) GaN thin-films. A second etch step in H<SUB>3</SUB>PO<SUB>4</SUB> solution additionally exposed a (1&cmb.macr;1&cmb.macr;22&cmb.macr;) plane, which is chemically stable in H<SUB>3</SUB>PO<SUB>4</SUB> solution. By repeating the chemical etch with KOH solution, the <I>m</I>-plane facets as seen in the original KOH etch step were recovered. The etching methods developed in our work can be used to control the surface morphologies of nonpolar and semipolar GaN-based optoelectronic devices such as light-emitting diodes and solar cells.</P> <P>Graphic Abstract</P><P>Chemical etching methods were developed to control the surface morphologies of nonpolar and semipolar GaN-based optoelectronic devices. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=c4cp02303j'> </P>
Jaehui Ahn,Geunwoo Ko,김지현,Michael A. Mastro,Jennifer Hite,Charles R. Eddy Jr. 한국물리학회 2010 Current Applied Physics Vol.10 No.2
This paper demonstrates the manipulation of neutral dielectric wires with high aspect ratio by a pulsed electric field. Dielectrophoretic (DEP) force and torque were employed to align the randomly positioned GaN nano- and micro-wires. A simulation of the DEP force alignment process confirmed the experimentally observed dependence on alignment yield to frequency and bias of the electric field. Current–voltage measurements of the GaN micro-wires, aligned by DEP force and torque to pre-patterned metal contacts,confirms that the direct manipulation of micro-sized wire with an electric field oscillated at a frequency of 10 kHz–5 MHz.