Organic thin-film transistors with a bottom bilayer gate dielectric having a low operating voltage and high operational stability
- Georgia Inst. of Technology, Atlanta, GA (United States)
This study reports on p-channel bottom-gate organic thin-film transistors (OTFT) that achieve low-voltage operation with a thin bilayer gate dielectric of CYTOP/HfO2 that also leads to high operational stability. A bottom-gate geometry allows the thickness of the gate dielectric to be reduced to 17 nm, thereby increasing the gate dielectric capacitance density to a value of up to 258 nF/cm2. All OTFTs yielded threshold voltages (VTH) lower than -1 V, thereby providing minimum operating voltage (gate to source voltage ~ VTH) of -1 V with field-effect mobility values in the range from 0.3 to 0.8 cm2/Vs and subthreshold swing values below 100 mV/dec. Operational stability during DC bias stress was found similar to that measured in devices with a top-gate geometry, with about 1% of drain current change after 6 h. Here, using a double-stretched exponential function, the operational stability characteristics were modeled. It was found that by increasing the metal oxide layer thickness, the threshold voltage can shift toward positive values under DC stress tests. For CYTOP layer thicknesses above 15 nm, a thicker CYTOP layer was found to shift the threshold voltage in the opposite direction toward negative values. Furthermore, these p-channel bottom-gate organic transistor with a bilayer gate dielectric of CYTOP/HfO2 combine high mobility, high operational stability, and lower voltage operation of -1 V compared to top-gate OTFTs.
- Research Organization:
- Georgia Institute of Technology, Atlanta, GA (United States)
- Sponsoring Organization:
- USDOE National Nuclear Security Administration (NNSA), Office of Nonproliferation and Verification Research and Development (NA-22)
- Grant/Contract Number:
- NA0003921
- OSTI ID:
- 1644040
- Journal Information:
- ACS Applied Electronic Materials, Vol. 2, Issue 9; ISSN 2637-6113
- Publisher:
- ACS PublicationsCopyright Statement
- Country of Publication:
- United States
- Language:
- English
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