Organic Field-effect Transistor - Device Design of Organic Field-effect Transistors

Device Design of Organic Field-effect Transistors

Three essential components of field-effect transistors are the source, the drain and the gate. Field-effect transistors usually operate as a capacitor. They are composed of two plates. One plate works as a conducting channel between two ohmic contacts, which are called the source and the drain contacts. The other plate works to control the charge induced into the channel, and it is called the gate. The direction of the movement of the carriers in the channel is from the source to the drain. Hence the relationship between these three components is that the gate controls the carrier movement from the source to the drain.

When this capacitor concept is applied to the device design, various devices can be built up based on the difference in the controller - i.e. the gate. This can be the gate material, the location of the gate with respect to the channel, how the gate is isolated from the channel, and what type of carrier is induced by the gate voltage into channel (such as electrons in an n-channel device, holes in a p-channel device, and both electrons and holes in a double injection device).

Classified by the properties of the carrier, three types of FETs are shown schematically in Figure 1. They are MOSFET (Metal Oxide Semiconductor Field-Effect Transistor), MESFET (MEtal Semiconductor Field-Effect Transistor) and TFT (Thin Film Transistor).