Dielectric Properties of and Charge Transport in Columnar Microfibrous Thin Films of Parylene C

Khawaji, Ibrahim H.; Chindam, Chandraprakash; Awadelkarim, Osama O.; Lakhtakia, Akhlesh

doi:10.1109/ted.2017.2711481

Cited by 11 publications

(9 citation statements)

References 62 publications

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“…The plane in which the microfibers are slanted is called the morphologically significant plane (MSP) and is identified as the xz plane in figure 1(b) [31]. The microfibers are 3-5 m m in diameter and spaced 2-3 m m apart [23,35]. The columnar μFTF must therefore by regarded as an anisotropic continuum in the context of mechanical vibrations up to a few tens of MHz in frequency [36,37], but effectively as an isotropic continuum when used as an insulator layer for electronics [38].…”

Section: K mentioning

confidence: 99%

“…Currently in flexible electronics, Parylene-C thin films can play three different roles-i.e.substrate, gate dielectric, and passivation layer-in the same device. If the relative permittivity κ can be lowered further, ParyleneC could also be used as a low-relativepermittivity material [23].Additionally, low-relativepermittivity Parylene-C thin films could be used in complementary metal-oxide-semiconductor devices. Thus, Parylene-C is expected to play different roles, thereby reducing material diversity in electronic devices.…”

Section: Introductionmentioning

confidence: 99%

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Selectablity of mechanical and dielectric properties of Parylene-C columnar microfibrous thin films by varying deposition angle

Khawaji

Chindam

Awadelkarim³

et al. 2017

Flex. Print. Electron.

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Columnar microfibrous thin films (μFTFs) were fabricated with a collimated flux of Parylene-C monomers directed at an angle 30 , 52 , 60 , 67 , 80 , 90} with respect to the substrate plane in a vacuum chamber. The porosity of the columnar μFTFs was found to decrease with the deposition angle v c and lie between 0.38 and 0.56. Both the static Young's modulus and the yield strength of the columnar μFTFs were found to be higher in the morphologically significant plane than in the plane normal to it. In both loading directions, static Young's moduli and yield strengths are about two orders of magnitude lower for the columnar μFTFs than the corresponding parameters of the bulk material, making the columnar μFTFs softer. The lowest relative permittivity of the fabricated columnar μFTFs in the 1-1000kHz range was found to be about 70% of that of the bulk material. The static Young's moduli, yield strengths, and the relative permittivity were correlated to the porosity, crystallinity, and the deposition angle. Both mechanical and dielectric properties of the columnar μFTFs can be controlled by selecting v c appropriately for application in flexible electronics.

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Section: K mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Selectablity of mechanical and dielectric properties of Parylene-C columnar microfibrous thin films by varying deposition angle

Khawaji

Chindam

Awadelkarim³

et al. 2017

Flex. Print. Electron.

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“…The microfiber diameter ranges from 3.3 to 5 μm and the center‐to‐center distance between nearest microfibers from 10 to 13 μm . The crystallinity, hydrophobicity, electrical properties, mechanical properties, and biomedical properties of μFTFs have been experimentally investigated.…”

Section: Introductionmentioning

confidence: 99%

Long‐wavelength infrared characteristics of multifunctional microfibrous thin films of Parylene C

Chindam

Venugopal

Lakhtakia

et al. 2019

Micro & Optical Tech Letters

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Calculations show that structurally chiral, three‐dimensionally periodic, microfibrous thin films (μFTFs) of Parylene‐C can function as both polarization‐insensitive and circular‐polarization‐selective photonic crystals in the long‐wavelength infrared regime. Careful engineering is required for bandstop filters in order to avoid the numerous absorption peaks of bulk Parylene‐C. The photonic functionality of the Parylene‐C μFTFs is in addition to their phononic, hydrophobic, and biomedical functionalities.

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“…Parylene C is commonly used as a dielectric material for electronic applications [1,3,4,5,6,7,8,9]. Pinhole-free films of this polymer function well as protection layers [10] to minimize device degradation caused by exposure to air and moisture.…”

Section: Introductionmentioning

confidence: 99%

“…In recent years, this polymer has been used for flexible substrates due to its desirable mechanical properties (yield strength of 55.1 MPa and static Young's modulus of 2.76 GPa) and the ease of deposition in both micrometer-and nanometer-thickness regimes [11]. In addition, we have recently shown that Parylene-C columnar microfibrous thin films are viable candidates for use as interlayer dielectrics [3,4,5].…”

Section: Introductionmentioning

confidence: 99%

Gold/Parylene-C/Pentacene Capacitor under Constant-Voltage Stress

Khawaji¹,

Brigeman²,

Awadelkarim³

et al. 2019

Preprint

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Degradation of metal-insulator-semiconductor (MIS) capacitors of gold/Parylene-C/Pentacene under constant voltage stress (CVS) was investigated to explore the electrical stability and reliability of Parylene C as a gate dielectric in flexible electronics. A stress voltage of fixed magnitude as high as 20 V, both negative and positive in polarity, was applied to each MIS capacitor at room temperature for a fixed duration as long as 10 s. The CVS effects on the capacitance-voltage curve-shift, the time-dependent leakage current, and the time-dependent dielectric breakdown were measured and analyzed. CVS is observed to induce charge in Parylene-C and its interfaces with gold and Pentacene. The net induced charge is positive and negative for, respectively, negative and positive gate bias polarity during CVS. The magnitude of the charge accumulated following positive gate CVS is significantly higher than that following negative gate bias CVS in the range of 4 to 25 nC cm −2 . In contrast, the leakage current during the negative gate stress is three orders of magnitude higher than that during the positive gate stress for the same bias stress magnitude. The charge buildup and leakage current are due to the trapping of electrons and holes near the Parylene-C/Pentacene interface as well as in the Parylene-C layer. Before the application of the CVS, a dielectric breakdown occurs at an electric field of 1.62 MV cm −1 . After the application of the CVS, the breakdown voltage decreases and the density of the trapped charges increases as the stress voltage increases in magnitude, with the polarity of the trapped charges opposite to that of the stress voltage. The magnitude and direction of the capacitancevoltage curve-shift depend on the trapping and recombination of electrons and holes in the Parylene-C layer and in the proximity of the Parylene-C/Pentacene interface during CVS.

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Dielectric Properties of and Charge Transport in Columnar Microfibrous Thin Films of Parylene C

Cited by 11 publications

References 62 publications

Selectablity of mechanical and dielectric properties of Parylene-C columnar microfibrous thin films by varying deposition angle

Selectablity of mechanical and dielectric properties of Parylene-C columnar microfibrous thin films by varying deposition angle

Long‐wavelength infrared characteristics of multifunctional microfibrous thin films of Parylene C

Gold/Parylene-C/Pentacene Capacitor under Constant-Voltage Stress

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