Nanoscale organic thin film transistors
Abstract
Organic thin film transistors (OTFTs) have attracted a large interest in emerging electronic technologies where large area coverage and low cost is required. The current delivered by the OTFT is inversely proportional to the channel length L, which motivated studies of OTFTs with submicron channel lengths. Past work has shown the characteristics of the OTFTs to degrade when L is below 100 nm, due to either poor charge injection at metal/organic semiconductor interface or "punch-through" effects. To explore whether those effects impose the inherent limitation in the performance of nanoscale organic transistors, state-of-the-art e-beam lithography was combined with organic semiconductor deposition techniques to fabricate OTFTs with channel lengths down to 30 nm. The devices employed pentacene film as the active layer and 30 nm thick SiO2 as the gate dielectric. The current-voltage characteristics of these devices exhibited the behavior expected for p-channel OTFTs and scaled gracefully with channel length and width. An improvement in gate modulation was achieved by replacing the SiO 2 with a native aluminum oxide layer. To further explore the scaling limit of organic transistors, sub-10 nm channel length pentacene OTFTs were fabricated. In order to avoid current leakage, a side guard structure was employed. The current-voltage characteristics of a sub-10 nm channel length pentacene transistor exhibited the behavior of a p-type OTFT. Various pentacene deposition process parameters and gate dielectric surface treatments were tested and were found to have a significant impact on device characteristics.
- Publication:
-
Ph.D. Thesis
- Pub Date:
- 2006
- Bibcode:
- 2006PhDT........45Z