Oxidized Graphene Transistors (GOT)

A transistor device configuration based on oxidized graphene.

Specifications

Precursor materialBamboo
Methoddouble thermal decomposition (DND) method
Electrical characterization
Input Curvesame input impedance behavior as conventional BJTs
Output Curve0.09713 to 150.0 mS, close to BJTs
Transfer Curve0.0136 to 0.149, far from BJTs
Reaction Curve0.614 to 0.9904, far from BJTs

Overview

This tech spec was submitted by Humberto Franco-Osorio as part of the University Technology Exposure Program.


Problem / Solution

Graphene’s dominion in material science proves an uncontested rise over the years. Various studies on how to maximize its properties are stacking up in number. Its impeccable thermal, mechanical, and electrical properties allow for a vast application, including its potential to revolutionize the electronics field. Graphene’s ability to mimic semiconductor properties when exposed to oxides makes it a viable replacement for silicon.

Using the double thermal decomposition method (DND), a transistor device using oxidized graphene (GO) is fabricated to obtain impedances similar to commercially-used transistors. The device configures a bipolar junction transistor model, implemented using organic materials like bamboo as a precursor.

Design

Manufacturing

The method of oxidation and decomposition obtained quartz substrate with GO-filmed coats exhibiting a narrow band gap behavior like that of semiconductor material. Isopropanol lets the detachment of GO films from the substrates before mechanically cutting and transferring them to bakelite sample holders. The holders, safetied with protective marks, enter the thermal evaporation system where the deposition of the electrical contacts occurs. To analyze the electrical behavior of oxidized graphene transistors (GOT), the transistor characterization calibrated at the University of Quindio is used. Its implementation obtains input, output, and transfer and reaction curves, detailing the device properties.

 

Electrical characterization

The initial input curve shows a little deviation from the expected behavior of a BJT, thus prompting adjustment in the GOT using the Shockley model that identifies various parameters. Upon carrying out the changes, GOT now follows the same input impedance behavior as conventional BJTs. The saturation current and ideality factor are both high. And thus imply the ambipolarity of the device—a transistor property allowing flow in two directions.

In the output curve, where the output voltage influences the current output when subjected to a constant input voltage, the admittance of the device can be calculated. These curves and calculations show that the current appears in negative and positive regions, another ambipolar description for a transistor. It also displays the output admittance as close to the magnitude of commercial BJTSs, ranging from 0.09713 to 150.0 mS.

The transfer curve, on the other hand, interprets the relationship between the input and output currents. This relationship determines the current amplification factor, which is vital in transistor operation as their application depends on current improvement. Calculations based on the curves show that this value ranges from 0.0136 to 0.149, quite far from expected BJT characteristics. It can be furthered that the device is independent of current controlled devices, attributing such to the recombination effect occurring in the equivalent base and emitter terminals.

Similarly, on the reaction curve, where the relationship of the output and input voltages are identified, computations obtained show discrepancies from BJT performance. The recorded value of 0.614 to 0.9904 means that the device demonstrates transistor behavior when dominated by a controlled voltage source.

From these curves, the GOT devices synthesized using the DND exude potential applications in the practice of electronics. As a benchmark, there is a boundless area in the study of oxidized graphene that can bring about massive changes in our dealing with electronic circuitry.

References

A research paper describing the challenge, design, and outcome of the research.

Humberto Franco-Osorio

Wevolver 2023