Browsing by Author "Wang, Chung-Hwa"

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Carbon attachment on the aluminum nitride gate dielectric in the pentacene-based organic thin-film transistors
(2009-03-15)
Zan, Hsiao-Wen
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Chou, Cheng-Wei
;
Wang, Chung-Hwa
;
Song, Ho-Tsung
;
Hwang, Jenn-Chang
This study presents carbon attachment on an aluminum nitride (AlN) gate dielectric to improve the device performance of pentacene-based organic thin-film transistors (OTFTs). This approach produces high OTFT performance on an aged AlN surface. A high mobility of 0.67 cm(2)/V s was achieved on an AlN surface aged for 14 days, compared to a mobility of 0.05 cm(2)/V s on an as-deposited AlN surface. This improvement in device performance is correlated with carbon attachment on the AlN surface, which lowers surface energy. The lowered surface energy made the surface less polar, as measured by a contact angle instrument. The chemical composition of the aged AlN surface was analyzed using x-ray photoelectron spectroscopy before pentacene deposition. Enhanced C=C bonding at 284.5 eV was observed on the aged AlN surface. These enhanced C=C bonds favored the growth of large pentacene islands in the initial growth stage, which may improve OTFT device performance.
Methane Exposure on the Aluminum Nitride Gate Dielectric in Pentacene-Based Organic Thin-Film Transistors
(2009)
Chou, Cheng-Wei
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Zan, Hsiao-Wen
;
Wang, Chung-Hwa
;
Chen, Wei-Tsung
;
Tsai, Li-Shiuan
The device performance of a pentacene-based organic thin-film transistor (OTFT) fabricated on an aluminum nitride (AlN) surface can be improved by exposing AlN to a methane (CH(4)) gas before device fabrication. The mobility of the OTFT was enhanced from 0.046 to 0.924 cm(2)/V s by exposing AlN to CH(4). Its threshold voltage was reduced from -4.5 to -1.9 V. After the CH(4) exposure, the reduced surface energy of AlN was correlated with the improvement of the OTFT performance. The reduction of surface energy was correlated with the replacement of O-C=O bonds by C-O bonds and hydrocarbon (CH(x)) on the AlN surface. (C) 2009 The Electrochemical Society. [DOI: 10.1149/1.3182823] All rights reserved.
Pentacene patterning on aluminum nitride by water dipping
(2008)
Zan, Hsiao-Wen
;
Chou, Cheng-Wei
;
Wang, Chung-Hwa
;
Yen, Kuo-Hsi
;
Hwang, Jenn-Chang
This study reports a pentacene patterning method that can be combined with conventional lithography to pattern pentacene film. The aluminum nitride (AlN) surface was patterned using a conventional photolithography process and then treated with oxygen (O(2)) plasma on uncovered AlN to modify surface polarity. Following pentacene deposition, the sample was dipped in water to remove pentacene from the O(2) plasma-treated area. The O(2) plasma-treated AlN surface was analyzed using X-ray photoelectron spectroscopy (XPS) before pentacene deposition. The polar surface energy changed from 13.2 to 114.4 mJ/m(2) when the AlN surface was treated with O(2) plasma at 100 W for 10 min. The polar surface energy was attributed to the increase of Al-O bonds on the surface based on XPS measurements. The intrusion energy of water was enhanced from 34.5 to 140.4 mJ/m(2) due to the polar surface energy induced by the O(2) plasma treatment. The enhancement of water intrusion energy and the polar surface energy explains the water-removable pentacene patterning mechanism. (C) 2008 The Electrochemical Society.