Research Method

2. Research Method

2.1. Design and Principle of Operation

OFET is an electronic component that works based on the current settings with the electric field. OFET called Unipolar Junction Transistor (UJT) because of the way it works based on the flow of majority carriers. Current flowing from D to S is controlled by a gate voltage (V G ). When there is no voltage V G , the drain current (I D ) is very low, and transistor is normal again. When V G increases, the charge carriers accumulated on the surface of the semiconductor and the insulator. Then, when the current I D increases associated with increased charge carrier, the transistor relapse on. This brief description is the working principle of OFET. OFET very similar to the inorganic FET, especially concerning the design and functionality [4, 13, 15]. These devices consist of three electrodes, source (S), drain (D) and gate (G), the gate dielectric as a gate insulator of a semiconductor material and organic material that forms the active layer. Organic materials such as organic molecules [4,13, 15] and polymer [21,

5, 7] can be used as the active layer. Many techniques Maximum Power Point Tracking (MPPT) that have been introduced and widely described by the researchers. References states that at least

19 different methods have been promoted, developed and implemented to increase solar photovoltaic [9]. Each method differs in complexity, the number of sensors used the cost and effectiveness [20].

OFET based on Organic semiconductors (OSC) and operates via a reversible second electric field application [3]. Both side of the electric field is an electric field which occurs between S/D vertical and between G with organic semiconductors. G electric field induces a charge carrier layer at the interface of the dielectric and the dielectric of the OSC, called "channel" Two basic parameters of the device is the channel length L is the distance between the contact electrodes S and D and W represents the channel width wide organic layer. The difference between the two configurations lies in the position of the metal source and drain electrodes. The position of the metal source and drain electrodes over the organic materials for OFET top contact, whereas of the organic material is bottom contact OFET.

The working principle OFET as follows: V G application, resulting in an electric field generated by the accumulation of charge carriers at the interface between G dielectric and the organic material to form channel. The number of free charge carriers V G dependent channel regions that are applied and can be varied. Therefore, the number of charge carriers between the semiconductor and the G dielectric will increase when V G is increased. At the time of the voltage applied to the D electrode, current will flow through channel between S and D. Thus it can be said that the magnitude of the current can be controlled by V G is applied, while D voltage is required to control the charge carriers from S to D. FinFET and cell-based JLT 6T-SRAM is designed to set up a back MOSFET and Junctionless conventional FinFET transistor [6].

Although research in the field of OFET very spacious [1, 18, 27] but there are still many factors challenge that should be concerned, among other things: the selection of organic molecules Although research in the field of OFET very spacious [1, 18, 27] but there are still many factors challenge that should be concerned, among other things: the selection of organic molecules

D. Therefore, for the good performance of OFET many parameters must be considered, such as the number of traps due to unwanted contamination, defects structure, result of an organic thin film deposition, contact resistance, formation of metal electrodes S and D leads to charge carrier injection in the molecule, degradation of molecules in the air.

2.2. OFET CuPc configuration Manufacture OFET based thin film CuPc done by making contact bottom structure such as (Figure 1). The stages of the manufacturing process, as follows: first washing, the substrate SiO 2 with ethanol in the ultrasonic cleaner. For the fabrication of OFET with bottom contact structure is performed as follows: after washing the substrate SiO 2 to clean, then carried the electrode deposition S/D on a layer of SiO 2 using a pure gold material with lithography method. Furthermore, CuPc deposed thin film.

Figure 1. OFET CuPc configuration scheme

2 Thin film growth technique as follows: cutting the substrate size 6.15 mm and distance between source to drain (L) is 100 μm, and then the substrate was washed using ultrasonic cleaner

Parmer core models. CuPc material with a mass of 200 mg inserted into the bell-jar. Furthermore, the substrate that has been cleaned is mounted on the right holder on top of the boot

which already contains CuPc. Then vacuuming VE until the pressure drops to 8.10 -4 Pa (about 4 hours). The evaporation process is done by providing a steady current of 45 A and wait until the

time limit specified .

2.3. OFET fabrication lithography process

Mechanical lithography include: coating photoresist using a spinner, next process preheating (prebake) aim to increase the adhesion between the resist to the layer below, the alignment and irradiation using a mask aligner, then the developer to generate a pattern on a resist and the lithography latter is heating end (post bake) which aims to strengthen resist. After lithography then the next step is etching. The purpose of etching to open the layer in places that are not covered by the resist. Resist that there should be discarded as useless and would contaminate the next process using a resist stripper.

Characterization of I-V metal contact showing the relationship between the current through the electronic device and voltage applied to terminal. Characteristics device are very important to determine the basic parameters of the devices and modeling the behavior in an electric circuit. Besides, the I-V characteristics of the active component are connected between the two electrodes utilized to estimate the material properties, such as conductivity and mobility. OFET based on OSC and operates through two reversible electric field application [12].

Gate field induces a charge carrier layer on the dielectric and the OSC dielectric interface, which is called a channel. The amount of channel capacitance depends on the dielectric and the G field. Mobility in the OSC describe continuous transfer electrons to the material and collect in the channel induced by the electric field D. I-V characterization of OFET CuPc is as follows. Electrodes from S connected to a grounded, while the G and D each connected with a bias retreat.

To determine the output characteristic graph of OFET, the need for robust measurement I D from S

to D by varying voltage at V D for each value of V G .