| Summary: | 碩士 === 國立交通大學 === 光電工程系所 === 94 === Due to fixable, low temperature process and low cost, application of organic thin film transistor on flat plane display is very suitable to fabricate low cost device. Usually, surface treatment is used to increase mobility of carrier transport in organic thin film transistor. Until now, without anyone analyze reliability of device which is treated. Therefore this paper studies variation of device with and without surface treatment under different DC and AC stress condition.
Firstly, we design Gated-Four-Probe (GFP) structure to extract characteristic of device in channel. Analysis of voltage distribution from Gated-Four-Probe can find that carrier transport mechanism of OTFT is consistent with carrier drift mechanism. Subsequently we fabricate Gated-Four-Probe (GFP) structure on different surface treatment substrate. The devices in this paper are separate to standard and two kinds of surface treatment. Standard device is cleaned by RCA clean and the other devices are treated by HMDS or ODMS. Initially, under DC stress condition we can find threshold voltage shift at positive gate bias stress is larger than at negative gate bias stress. Whether at positive or negative gate bias stress condition, Vth shift of devices with surface treatment are larger than standard devices. The extracted parameters from Gated-Four-Probe (GFP) indicate that pentacene film is not changed with time. Therefore reliability issues lie in the gate insulator or SAM layer degradation. Under AC stress condition, Vth shift of standard devices are obvious decrease. It appears that standard devices have better reliability at AC operation. But Vth shift of devices with HMDS and ODMS still have lager value.
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