| Autor: |
Horowitz, Gilles, Hajlaoui, Riadh, Delannoy, Philippe, Horowitz, Gilles, Hajlaoui, Riadh, Delannoy, Philippe |
| Zdroj: |
Journal de Physique III; April 1995, Vol. 5 Issue: 4 p355-371, 17p |
| Abstrakt: |
Conductivity and field-effect mobility measurements as a function of temperature have been carried out on unsubstituted sexithiophene (6T) and end-substituted dihexyl- sexithiophene (DH6T). At temperatures higher than 150 K, the conductivity is thermally activated, whereas the field-effect mobility presents a gate-bias dependent activation energy. Importantly, the field-effect mobility tends to saturate at both high gate voltages and high temperatures. The data were analyzed within the frame of a multiple thermal trapping and release model. The distribution of localized states near the transport level has been determined for both compounds, and was fitted to a double exponential distribution, which can be compared to that of hydrogenated amorphous silicon (a-Si:H). The localized trap states in 6T and DH6T originate from grain boundaries. The lower mobility of the unsubstituted compound can be attributed to the corresponding higher density of traps. At temperatures lower than 150 K, thermally activated hopping becomes the dominant transport mechanism, but multiple trapping can also be present in the accumulation layer of a field-effect transistor at high gate voltages. |
| Databáze: |
Supplemental Index |
| Externí odkaz: |
|
