Conference Program - LOPE-C 2011

SCIENTIFIC CONF. | WEDNESDAY-JUNE 29, 2011
Track 4
Organic Transistors (02:30 pm - 04:00 pm) | LOCATION HARMONIE D / LEVEL C2
03:20 pm Measurement, analysis, and modeling of 1/f noise in pentacene TFTs
Mr Hongki Kang,
UC Berkeley, PhD student, United States
The use of organic TFTs has been suggested for low-cost and large-area applications such as RFID and various types of sensors. To date, most research has been
focused on performance and stability optimization of the same. However, particularly for sensing applications, it is equally important to know how immune OTFTs are to
unwanted noise signals because typical OTFT current levels are small and their operating frequency range is typically low, such that 1/f noise is dominant. Therefore, it is
crucial to understand the mechanisms underlying low frequency noise (LFN) in OTFTs and to develop a model to estimate the noise accurately. Here we present
experimental results of the unique LFN characteristics in OTFTs with comprehensive mechanistic analysis and modeling using a unified noise model.
For more than four decades, 1/f noise in conventional MOSFETs has been studied intensively, and it is generally believed that there are mainly two dominant sources of 1/f
noise ? fluctuations in the number of carriers and in the carrier mobility. In previous work on LFN in OTFTs, there have been debates about which mechanism is more
applicable to OTFTs. We conducted drain current noise measurements for pentacene-based OTFTs having different grain size, film thickness and operating region. From
our experimental results, we conclude that carrier density fluctuations due to trapping/de-trapping of carriers by/from traps in the semiconductor are the dominant source.
The effects of semiconductor grain size, semiconductor film thickness and operating region on LFN are presented.
We also show that the unified noise model which is analytically derived for conventional MOSFETs can be applied to OTFTs with a notable feature which reveals that there
is an additional mobility fluctuation induced by acceptor-like traps in the semiconductor.
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