First Results

Organic Dielectric

 This week, before the bench inspection, we worked on the data we have been provided. We spent some time working out the best way to process the numbers, and ended up using half MatLab, half Excel. The maths behind the plots was generated using Excel and than imported to MatLab. The figures are of great quality and we hope they will look good on our posters, along with some explanations.
 Unfortunately the results are not easy to interpretate hence we will need to make some changes in the plots in order to make the shapes(slope, intercept) more visible, this is just a matter of time.

Alumina dielectric

The last week

In this week, we got all plots by MATLAB, which are J-E, Fowler Nordheim (ln(J/E^2) & 1/E) and Poole-Frenkel emission (ln(J/E) & sqrt(E)) for organic dielectric and Alumina dielectric respectively. Also, we chose the best part of Poole-Frenkel emission which can be seen as a straight line and figured out the slopes for forward bias.

In the fifth meeting with our supervisor, she gave some suggestions for the poster which needs to be displayed on the Bench Inspection day. There should be three sections on the poster.

First: The project objective; why doing the project; How useful to engineering
Second: Basic theory; Applications of OTFTs
Third: Analysis and Results

Of course, we should add some references if need. Additional, to breakdown field, we should compare them and find the difference to give a explain.

The date of the Bench Inspection day: 8th March, 2013

Plots

Acorrding to the data, we tried to determine the current density, oxide thickness, electric field and conduction process in the two different dielectrics. To determine the conduction process, we choose to observe the line sharp of the specific relationship between current density and electric field. If the value of ln(J/E^2) is directly proportional to the value of (1/E), it is Tunneling process. If the value of ln(J/E) is directly proportional to the value of sqrt(E), it is Frenkel-Poole process. But unfortunatly, we have not got the right plots for these properties so far.

In the meeting with our supervisor this week,  we discussed the appropriate oxide thinknesses and reasonable values for Aluminium Oxide dielectric and Organic dielectric. This gave us a better idea how to verify our results.

Next Meeting 27/02/2013

Data Sheets

After a good week of personal research and study on conduction mechanisms, at this meeting we discussed the methods of determining the leakage currents in an Oxide dielectric. Using a MIM (metal insulator metal ) capacitor we are going to use Current vs Voltage and Voltage Capacitance characteristics to find which conduction process occurs in the insulator.

The data is collected from two capacitors ei: One with Organic insulator and One with Aluminium oxide insulator. 

Frenkel Poole emission is due to emission of trapped electrons into the conduction band. This is less common in Silicon dioxide because it is more perfect than Aluminium or Titanium oxides. 

 Fowler-Nordheim tunneling is the most common conduction mechanism in insulators under high fields. The energie barrier between the metal contact and insulator reduce when a high voltage is applied. 

This mechanisms can be detected after plotting the graphs. 

First Objectives

This week we created some steps for our research. We believe this can make our task easier and more productive.

On 06/02/2013 we had a meeting with Dr. M. Raja and determined the basic knowledge background we need to develop in order to have a better understanding on the specific subject 'leakage currents'.

We have been provided with a brief explanation on the transistor architecture and their types(for the record: our study is based on bottom gate/botton contact transistors because of their simplicity of processing)

Referance to the Organic semiconductor GATE and CONTACTS are bottom, hence the name 'Botoom Gate/Botoom Contact'

Because of the time limitation we will do the strictly necessary part, which is study of leakage currents in a capacitor model with a organic insulator.

There are two Basic Conduction Processes in Insulators that are of interest to us at this stage. Tunneling and Frankel Poole emission. We have to make sure to get a solid knowledge on these two by the next meeting.

Our main book of referance, so far is "PHYSICS OF SEMICONDUCTOR DEVICES" (S.M SZE KWONK K. NG. 2007)

next meeting 15/02/2013

　

Opening Post

Hello everyone! We are group 39 and our topic for Second Year project is "Study leakage currents in organic thin film transistors". Our supervisor is  Dr Munira Raja. Her current research interests include development of novel designs and processes for low-cost flexible organic circuits and she will be guiding us with appropriate steps. After our first meeting we got a general idea of the topic we should concentrate on during our private research. The Organic Transistors are now a popular research subject among research groups around the glob and big electronic companies see a great perspective in this technology.