Publications by authors named "Jae-Seong Park"

8 Publications

  • Page 1 of 1

Continuous-wave quantum dot photonic crystal lasers grown on on-axis Si (001).

Nat Commun 2020 Feb 20;11(1):977. Epub 2020 Feb 20.

Department of Electronic and Electrical Engineering, University College London, Torrington Place, London, WC1E 7JE, UK.

Semiconductor III-V photonic crystal (PC) laser is regarded as a promising ultra-compact light source with unique advantages of ultralow energy consumption and small footprint for the next generation of Si-based on-chip optical interconnects. However, the significant material dissimilarities between III-V materials and Si are the fundamental roadblock for conventional monolithic III-V-on-silicon integration technology. Here, we demonstrate ultrasmall III-V PC membrane lasers monolithically grown on CMOS-compatible on-axis Si (001) substrates by using III-V quantum dots. The optically pumped InAs/GaAs quantum-dot PC lasers exhibit single-mode operation with an ultra-low threshold of ~0.6 μW and a large spontaneous emission coupling efficiency up to 18% under continuous-wave condition at room temperature. This work establishes a new route to form the basis of future monolithic light sources for high-density optical interconnects in future large-scale silicon electronic and photonic integrated circuits.
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http://dx.doi.org/10.1038/s41467-020-14736-9DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7033092PMC
February 2020

Genome Sequence of Grapevine Virus T, a Novel Foveavirus Infecting Grapevine.

Genome Announc 2017 Sep 14;5(37). Epub 2017 Sep 14.

Department of Agricultural Biotechnology, College of Agriculture and Life Sciences, Seoul National University, Seoul, Republic of Korea

Here, we report the genome sequence of grapevine virus T (GVT), a novel single-stranded RNA virus identified from a transcriptome of grapevine. The genome of GVT is 8,701 nucleotides in length and encodes five open reading frames. GVT is a putative member of the genus in the family .
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http://dx.doi.org/10.1128/genomeA.00995-17DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5597771PMC
September 2017

Genome Sequence of Grapevine Virus K, a Novel Vitivirus Infecting Grapevine.

Genome Announc 2017 Sep 14;5(37). Epub 2017 Sep 14.

Department of Agricultural Biotechnology, College of Agriculture and Life Sciences, Seoul National University, Seoul, Republic of Korea

Here, we report the genome sequence of grapevine virus K (GVK), a novel single-stranded RNA virus identified from a transcriptome of grapevine. The genome of GVK is 7,476 nucleotides in length and encodes 5 open reading frames. GVK is a putative member of the genus in the family .
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http://dx.doi.org/10.1128/genomeA.00994-17DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5597770PMC
September 2017

Flexible Polymer/Metal/Polymer and Polymer/Metal/Inorganic Trilayer Transparent Conducting Thin Film Heaters with Highly Hydrophobic Surface.

ACS Appl Mater Interfaces 2017 Sep 14;9(38):33129-33136. Epub 2017 Sep 14.

Chemical Materials Solutions Center, Korea Research Institute of Chemical Technology , Daejeon 34114, Republic of Korea.

Polymer/metal/polymer and polymer/metal/inorganic trilayer-structured transparent electrodes with fluorocarbon plasma polymer thin film heaters have been proposed. The polymer/metal/polymer and polymer/metal/inorganic transparent conducting thin films fabricated on a large-area flexible polymer substrate using a continuous roll-to-roll sputtering process show excellent electrical properties and visible-light transmittance. They also exhibit water-repelling surfaces to prevent wetting and to remove contamination. In addition, the adoption of a fluorocarbon/metal/fluorocarbon film permits an outer bending radius as small as 3 mm. These films have a sheet resistance of less than 5 Ω sq, sufficient to drive light-emitting diode circuits. The thin film heater with the fluorocarbon/Ag/SiN structure exhibits excellent heating characteristics, with a temperature reaching 180 °C under the driving voltage of 13 V. Therefore, the proposed polymer/metal/polymer and polymer/metal/inorganic transparent conducting electrodes using polymer thin films can be applied in flexible and rollable displays as well as automobile window heaters and other devices.
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http://dx.doi.org/10.1021/acsami.7b09837DOI Listing
September 2017

Use of a patterned current blocking layer to enhance the light output power of InGaN-based light-emitting diodes.

Opt Express 2017 Jul;25(15):17556-17561

We employed a patterned current blocking layer (CBL) to enhance light output power of GaN-based light-emitting diodes (LEDs). Nanoimprint lithography (NIL) was used to form patterned CBLs (a diameter of 260 nm, a period of 600, and a height of 180 nm). LEDs (chip size: 300 × 800 µm) fabricated with no CBL, a conventional SiO CBL, and a patterned SiO CBL, respectively, exhibited forward-bias voltages of 3.02, 3.1 and 3.1 V at an injection current of 20 mA. The LEDs without and with CBLs gave series resistances of 9.8 and 11.0 Ω, respectively. The LEDs with a patterned SiO CBL yielded 39.6 and 11.9% higher light output powers at 20 mA, respectively, than the LEDs with no CBL and conventional SiO CBL. On the basis of emission images and angular transmittance results, the patterned CBL-induced output enhancement is attributed to the enhanced light extraction and current spreading.
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http://dx.doi.org/10.1364/OE.25.017556DOI Listing
July 2017

Formation of an indium tin oxide nanodot/Ag nanowire electrode as a current spreader for near ultraviolet AlGaN-based light-emitting diodes.

Nanotechnology 2017 Jan 19;28(4):045205. Epub 2016 Dec 19.

Department of Materials Science and Engineering, Korea University, Seoul 02841, Korea.

Indium tin oxide (ITO) nanodots (NDs) were combined with Ag nanowires (Ag NWs) as a p-type electrode in near ultraviolet AlGaN-based light-emitting diodes (LEDs) to increase light output power. The Ag NWs were 30 ± 5 nm in diameter and 25 ± 5 μm in length. The transmittance of 10 nm-thick ITO-only was 98% at 385 nm, while the values for ITO ND/Ag NW were 83%-88%. ITO ND/Ag NW films showed lower sheet resistances (32-51 Ω sq) than the ITO-only film (950 Ω sq). LEDs (chip size: 300 × 800 μm) fabricated using the ITO NDs/Ag NW electrodes exhibited higher forward-bias voltages (3.52-3.75 V at 20 mA) than the LEDs with the 10 nm-thick ITO-only electrode (3.5 V). The LEDs with ITO ND/Ag NW electrodes yielded a 24%-62% higher light output power (at 20 mA) than those with the 10 nm-thick ITO-only electrode. Furthermore, finite-difference time-domain (FDTD) simulations were performed to investigate the extraction efficiency. Based on the emission images and FDTD simulations, the enhanced light output with the ITO ND/Ag NW electrodes is attributed to improved current spreading and better extraction efficiency.
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http://dx.doi.org/10.1088/1361-6528/28/4/045205DOI Listing
January 2017

Highly reliable Ti-based ohmic contact to N-polar n-type GaN for vertical-geometry light-emitting diodes by using a Ta barrier layer.

Opt Express 2014 May;22 Suppl 3:A759-64

The formation of thermally stable and low resistance Ti/Al-based ohmic contacts to N-polar n-GaN for high-power vertical light-emitting diodes (VLEDs) using a Ta diffusion barrier is presented. Before annealing, both Ti/Al/Au and Ti/Ta/Al/Au contacts reveal ohmic behavior with specific contact resistances of 2.4 × 10⁻⁴ and 1.2 × 10⁻⁴ Ωcm², respectively. However, unlike the Ti/Al/Au samples that are electrically degraded with increasing annealing time at 250 °C, the Ti/Ta/Al/Au samples remain thermally stable even after annealing for 600 min. LEDs fabricated with the Ti/Ta/Al/Au contacts yield 8.3% higher output power (at 300 mA) than LEDs with the Ti/Al/Au contact. X-ray photoemission spectroscopy results show that the Ta layer serves as an efficient barrier to the indiffusion of oxygen toward the GaN. On the basis of the XPS and electrical results, the annealing dependence of the electrical characteristics of Ti/Al-based contacts are described and discussed.
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http://dx.doi.org/10.1364/OE.22.00A759DOI Listing
May 2014

Near ultraviolet InGaN/AlGaN-based light-emitting diodes with highly reflective tin-doped indium oxide/Al-based reflectors.

Opt Express 2013 Nov;21(22):26774-9

The enhanced light output power of a InGaN/AlGaN-based light-emitting diodes (LEDs) using three different types of highly reflective Sn-doped indium oxide (ITO)/Al-based p-type reflectors, namely, ITO/Al, Cu-doped indium oxide (CIO)/s-ITO(sputtered)/Al, and Ag nano-dots(n-Ag)/CIO/s-ITO/Al, is presented. The ITO/Al-based reflectors exhibit lower reflectance (76 - 84% at 365 nm) than Al only reflector (91.1%). However, unlike Al only n-type contact, the ITO/Al-based contacts to p-GaN show good ohmic characteristics. Near-UV (365 nm) InGaN/AlGaN-based LEDs with ITO/Al, CIO/s-ITO/Al, and n-Ag/CIO/s-ITO/Al reflectors exhibit forward-bias voltages of 3.55, 3.48, and 3.34 V at 20 mA, respectively. The LEDs with the ITO/Al and CIO/s-ITO/Al reflectors exhibit 9.5% and 13.5% higher light output power (at 20 mA), respectively, than the LEDs with the n-Ag/CIO/s-ITO/Al reflector. The improved performance of near UV LEDs is attributed to the high reflectance and low contact resistivity of the ITO/Al-based reflectors, which are better than those of conventional Al-based reflectors.
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http://dx.doi.org/10.1364/OE.21.026774DOI Listing
November 2013