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Proceedings Paper

Vertical organic transistors
Author(s): Liping Ma; Shenghan Li; Yang Yang
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Paper Abstract

A capacitor that basically consists of two parallel metal plates with dielectric materials in between, can store charge at the two inner surfaces of the metal plates when a voltage bias is applied. As the thickness of the metal-plate electrodes decrease to nanometers range, we find an interesting physical phenomenon, i.e., the stored charges can modify the physical properties of the semiconductor layer coated on top of it. This discovery leads us to demonstrate a whole-new concept field-effect transistor, a vertical organic transistor with a novel device structure by stacking gate-source-drain vertically. This vertical stack consists of an active cell (drain/organics/source) on top of a capacitor cell (source/dielectrics/gate). When the gate (capacitor) is biased, charges are stored in the capacitor cell. As the thickness of the source electrode is thin enough, typically in the nanometer range, the active cell can also sense the stored charges within the capacitor cell, and, subsequently, modulate the charge injection from the source into the organics. This unique device structure provides an extremely short "channel length" and large channel conduction area. As a result, we achieved organic transistors with low working voltage (less than 5 V), high current output (up to 10 mA or 4 A/cm2), and high ON/OFF ratio (up to 4×106). This device solves two long-standing issues with organic transistors, high working voltages and low current output. This novel device with its enhanced operating characteristics opens new directions for organic transistors and their applications. The device operation mechanism is different from traditional field effect transistors, where we proposed an injection-controlled mechanism, which can basically explain the observed electrical phenomenon of our vertical transistors.

Paper Details

Date Published: 22 September 2005
PDF: 8 pages
Proc. SPIE 5940, Organic Field-Effect Transistors IV, 59400V (22 September 2005); doi: 10.1117/12.618583
Show Author Affiliations
Liping Ma, Univ. of California/Los Angeles (United States)
Shenghan Li, Univ. of California/Los Angeles (United States)
Yang Yang, Univ. of California/Los Angeles (United States)

Published in SPIE Proceedings Vol. 5940:
Organic Field-Effect Transistors IV
Zhenan Bao; David J. Gundlach, Editor(s)

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