Results and Analysis

3. Results and Analysis

3.1. OFET Fabrication Process Lithography process (Figure 2) OFET fabrications based thin film of CuPc on a SiO 2 substrate to form an electrode S, D and G are seen from above.

Figure 2. OFET CuPc fabrication process: (a) Electrodes S and D has not been patterned, and the

deposition of Au. (b) The electrodes S and D has not been done patterned and cutting each sample. (c) Electrodes S and D already patterned. (d) Electrodes S, D and G already patterned.

3.2. Characteristics OFET

Characterization of I-V semiconductor contacts indicates the relationship between the current through the electronic device and voltage at terminals. Characteristics to determine the basic parameters of the device and modeling the behavior of the circuit [19]. Besides, I-V characteristics of active component connect two electrodes for predicting the properties of conductivity and mobility. OFET characterization the results can be seen in Figure 3. The voltage

V GS is varied, ie: -3 V; -1.5 V; 0 V; 1.5 V. 3V.

Figure 3. Characteristics OFET with channel length of 100 μm

OFET characteristic curve (Figure 3) shows that the increase in the voltage V DS causes, current I D will also be increased up to the saturation point of the transistor, as described in Ohm's law. If V DS increased, depletion region continues to rise so that eventually occurs in conditions of

a cut-off voltage. While voltage V D which led to a cut-off and called cut-off failure despite an increase in value of V DS is increased. OFET drain current I D at time a drain current and maximum is achieved when V GS =0 V and V DS >│V P │. At cut-off area, I D has a fixed value though and V DS a cut-off voltage. While voltage V D which led to a cut-off and called cut-off failure despite an increase in value of V DS is increased. OFET drain current I D at time a drain current and maximum is achieved when V GS =0 V and V DS >│V P │. At cut-off area, I D has a fixed value though and V DS

region, where change in drain current (I D ) will change the V D .

On the characteristics of OFET with a channel length of 100 μm having an active region

V -9

A. While the OFET saturation region is at a V D voltage is greater than 9.2 V, and this is an area cut off. In Figure 3 current I DS plotted as a function of V DS for a variety of different V GS voltage applied to electrodes, which serves as a gateway. Saturation region and linear evident with increasing voltage V DS . At time of low-voltage V DS , the current I DS follow Ohm's law and is proportional to voltage V DS . Therefore

DS is 1.2 V to 9.2 V and current I DS 1.10 A until 1.28. 10

V DS increases, voltage that is measured relative to source. This can be done during the change voltage channels from 0 to V DS . Thus the voltage between the gate and points along the channel decreases from V GS at the source V DS -V GS at the end of the drain. Characteristic curve (I DS -V DS ) are not continuous as a straight line, but a curved line (non-linear), in this state is known as the pinch-off of the conductive channel transistor. Therefore it can be said that the observation of the situation is due to the saturation of I DS pinch-off of channel [14].

Figure 3 shows that drain current is effectively influenced by V GS . Drain current (I DS ) OFET increased by a negative V GS . These data indicate that the field effect device with the operation of the p-type accumulation mode. The characteristics of a transistor are their linear region and saturation of the curve V DS to I DS . Based on Figure 3, the results did not reveal any current in a saturation state. This can be caused by the threshold voltage (V T ) OFET is too large or has not reached D and V GS that will make the conduction path between D and S depleted. While the tendency linear region that is almost similar to the current characteristics of the diodes. This can be caused by a considerable difference between the work function of D and S electrode work function CuPc. Work function difference is large enough lead electrode and CuPc non-ohmic contact form or forming the junction between the electrode and CuPc.