• Transactions on Electrical and Electronic Materials
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• v.16 no.3
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• pp.142-145
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• 2015

In this work, open stubs were fabricated on a polyether sulfone (PES) substrate, and their basic radio frequency (RF) characteristics were investigated for application to RF matching components of a flexible monolithic microwave integrated circuit (MMIC). According to the results, an open stub employing coplanar waveguide (OSCPW) on PES exhibited much lower loss than that on silicon substrate. The OSCPW with a length of $500{\mu}m$ on PES showed capacitance values of 0.031 ~ 0.044 pF from 0.5 to 50 GHz. For application to a relatively high-value capacitive matching, an open stub employing a fishbone-type transmission line (OSFTTL) was fabricated on PES, and its characteristics were investigated. The OSFTTL showed much higher capacitance values than the OSCPW due to the high effective permittivity value. Specifically, the OSFTTL on PES showed capacitance values of 0.066 ~ 0.24 pF from 0.5 to 50 GHz, which are higher than those for the open stub on silicon substrate. The above results indicate that the OSCPW and OSFTTL on PES can be effectively used for application to low/high-value capacitive matching components on microwave and millimeter wave flexible MMIC. To the best of the authors' knowledge, this work is the first report of the investigation of RF capacitive matching components on PES substrate.

• ETRI Journal
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• v.36 no.1
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• pp.106-115
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• 2014

In this work, the coplanar waveguide is fabricated on a PES (poly[ether sulfone]) substrate for application to a flexible monolithic microwave integrated circuit, and its RF characteristics were thoroughly investigated. The quality factor of the coplanar waveguide on PES is 40.3 at a resonance frequency of 46.7 GHz. A fishbone-type transmission line (FTTL) structure is also fabricated on the PES substrate, and its RF characteristics are investigated. The wavelength of the FTTL on PES is 5.11 mm at 20 GHz, which is 55% of the conventional coplanar waveguide on PES. Using the FTTL, an impedance transformer is fabricated on PES. The size of the impedance transformer is $0.318mm{\times}0.318mm$, which is 69.2% of the size of the transformer fabricated by the conventional coplanar waveguide on PES. The impedance transformer showed return loss values better than -12.9 dB from 5 GHz to 50 GHz and an insertion loss better than -1.13 dB in the same frequency range.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.59 no.1
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• pp.113-115
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• 2010

In this study, ZnO films have been grown on PES(polyethersu]fone) substrate by PLD(pulsed laser deposition) and characterized as a change of laser density and substrate temperature. Growing conditions were changed with substrate temperatures ranging from 50 to $200^{\circ}C$ and laser densities ranging from $0.2\sim0.4 J/cm^2$. Optical and structural properties were measured by XRD, SEM, AFM, PL measurement.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.20 no.12
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• pp.1072-1076
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• 2007

We prepared the Al doped ZnO (AZO) thin film on polyethersulfon (PES) without any substrate heating by Facing Targets Sputtering (FTS) system. FTS system has two different facing targets. One is ZnO doped the content of Al 2 wt% and the other is Zn in order to decrease resistivity. The electrical, structural and optical properties of AZO thin films were investigated. To evaluate the as-deposited thin film properties, we employed four-point probe (CMT-R100nw, Changmin), Surface profiler (Alpha-step, Tencor), UV/VIS spectrometer (HP), X-ray diffractometer (XRD, Rigaku) and Field Emission Scanning Electron Microscopy (FESEM, Hitachi S-4700). As a result, We obtained that AZO thin film deposited on PES substrate at a DC Power of 150 W, working pressure of 1 mTorr and $O_2$ gas flow ratio of 0.2 exhibited the resistivity of $4.2{\times}10^{-4}\;[{\Omega}cm]$ and the optical transmittance of about 85 % in the visible range.

• ETRI Journal
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• v.37 no.1
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• pp.128-137
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• 2015

In this work, a fishbone-type transmission line employing a comb-type ground plane (FTLCGP) was fabricated on polyethersulfone (PES) substrate, and its RF characteristics were thoroughly investigated. According to the results, it was found that the FTLCGP on PES showed periodic capacitance values much higher than other types of transmission lines due to a coupling capacitance between the signal line and ground, which resulted in a reduction of wavelength and line width. Using the theoretical analysis, we also extracted the bandwidth characteristic of the FTLCGP on PES. According to the result, the FTLCGP structure showed a cut-off frequency of 280 GHz.

• Journal of the Microelectronics and Packaging Society
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• v.14 no.1
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• pp.27-31
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• 2007

The cpapcitors with MIM(metal-insulator-metal) structures using PVP gate insulation films were prepared for the application of flexible organic thin film transistors (OTFT). The co-polymer organic insulation films were synthesized by using PVP(poly-4-vinylphenol) as a solute and PGMEA(propylene glycol monomethyl ether acetate) as a solvent. The cross-linked PVP insulation films were also prepared by addition of poly(melamine-co-formaldehyde) as thermal hardener. The leakage current of the cross- linked PVP films was found to be about 1.3 nA on Al/PES(polyethersulfone) substrate, whereas, on ITO/ glass substrate was about 27.5 nA indicating improvement of the leakage current at Al/PES substrates. Also, the capacitances of all prepared samples on ITO/glass and Al/PES substrates w ere ranged from 1.0 to $1.2nF/cm^2$, showing very similar result with the calculated capacitance values.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.15 no.7
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• pp.1559-1563
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• 2011

We fabricated gallium doped ZnO (GZO, 5 wt% Ga) thin films on PES (polyethersulfon) substrate with RF magnetron sputtering and investigated optical and electrical properties for various substrate temperatures ($50{\sim}200^{\circ}C$). All GZO thin film has c-axis preferred orientation without reference to deposition conditions. As a result of AFM analysis, the GZO thin film deposited at $200^{\circ}C$ exhibited the lowest surface roughness of 0.196nm. The transmittance of GZO thin films were above 80% and Burstein-Moss effect was observed. In the analysis of Hall measurement, we confirmed that the GZO thin film deposited at $200^{\circ}C$ showed the lowest resistivity of $6.93{\times}10-4{\Omega}{\cdot}cm$ and the highest carrier concentration of $7.04{\times}1020/cm^3$.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.06a
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• pp.442-443
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• 2006

Electrical, optical, surface, and structural properties of amorphous indium zinc oxide (IZO) films grown on $SiO_2$/PES/$SiO_2$ substrate by a RF sputtering in pure Ar ambient at room temperature were investigated. A sheet resistance of $13.5\;{\Omega}{\square}$, average transmittance above 85 % in 550 nm, and root mean square roughness of $10.5\;{\AA}$ were obtained even in the IZO layers grown at room temperature in pure Ar ambient. Without addition of oxygen gas during IZO sputtering process, we can obtain high quality IZO anode films from the specially synthesized oxygen rich IZO target. XRD result shows that the IZO films grown at room temperature is completely amorphous structure due to low substrate temperature. In addition, the electrical and optical properties of the flexible OLED fabricated on IZO/$SiO_2$/PES/$SiO_2$ is critically influenced by the electrical properties of a IZO anode. This findings indicate that the IZO/$SiO_2$/PES/$SiO_2$ is a promising anode/substrate scheme for realizing organic based flexible displays.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.06a
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• pp.405-406
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• 2008

The amorphous indium zinc oxide (IZO) thin films were deposited on polyethersulfone (PES) and glass substrates by facing targets sputtering. IZO thin films deposited as functions of gas flow ratio on PES and glass substrates, respectively. The electrical, optical and structural properties of IZO thin films were evaluated by a Hall Effect Measurement, an X-Ray Diffractormeter, UV/VIS spectrometer in visible range and a scanning electron microscopy, respectively. As-deposited IZO thin films exhibited resistivity of $5.4\times10^{-4}$ and $4.5\times10^{-4}$ [$\Omega$-cm] on PES and glass substrates, respectively. The optical transmittance showed over 85% in the visible region on PES and glass substrates.

• Journal of the Semiconductor & Display Technology
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• v.8 no.3
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• pp.57-60
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• 2009

Transparent electrode ZnO:Al(AZO)films were deposited on a PES (polyethersulfone) polymer substrate for thin film solar cells applications. A PES substrate with a thickness of 0.2mm and transmittance > 90% in the visible range was used because it is light weight and can deform easily. AZO thin films were prepared at a fixed DC power, $PO_2\;=\;P(O_2)/[P(O_2)\;+\;P(Ar)]$, and various substrate temperatures. The properties of AZO thin films were examined by X-ray diffraction, UV/VIS spectroscopy, four-point probe, Hall measurements, and field emission scanning electron microscopy. The lowest resistivity of all the films was $4.493\;{\times}\;10^{-4}\;[\Omega-cm]$ and the transmittance was > 80% in the visible range.