danielrpowell
New member
Hi everyone,
I'm not sure whether this is the right forum to ask this type of question. All the posts I see on here are discussing companies, but I figured I'd give it a shot anyway. I'm a PhD student studying organic semiconductors, and I'm building an organic thin-film transistor measurement system. I am using a Keithley 2636B SMU to measure the output characteristics of my transistors. I have been able to reproduce standard curves for industrial standard MOSFETs, but when I make my own I get very strange results. My MOSFETs are made on silicon wafers with an SiO2 surface dielectric that is 25 nm - 25 um thick. I have been trying to use P3HT as a standard, where the P3HT layer is spin-cast from a 2% by weight solution (chlorobenzene as the solvent) and is about 200 nm thick. I then deposit 100 nm Ag electrodes in a vacuum chamber. The devices are about 10 mm wide, about 2 mm long, and have a channel length of about 0.5 mm. To make contacts I am using pins on micro-positioners that are connected directly to the keithley system. I make contact to the source and drain, and then I scratch the silicon wafer down to the silicon and make my gate contact where I scratch. When I sweep the drain voltage to, say, -30 V I get a drain current that looks somewhat diodic. As I ramp up the gate voltage to, say, -30 V I don't see any gate activity. The curves are reproduced at all gate-voltages. I know that most organic MOSFETs in research labs are pushed up to +/- 100 V on both the drain and the gate, but mine don't show any activity at these high voltages. Again, I get normal output characteristics on industry MOSFETs, but my own don't work. Any suggestions on:
1-What is a good organic material to use as a standard?
2-What device architecture should I be using?
3-Is it OK to use needles as contacts to such large devices? I am thinking I may need to make the switch to larger, blunt contact pins.
4-Are there any good resources on setting up and standardizing MOSFET measurement systems? I have scoured the web and can't find anything.
Thank you for your help.
I'm not sure whether this is the right forum to ask this type of question. All the posts I see on here are discussing companies, but I figured I'd give it a shot anyway. I'm a PhD student studying organic semiconductors, and I'm building an organic thin-film transistor measurement system. I am using a Keithley 2636B SMU to measure the output characteristics of my transistors. I have been able to reproduce standard curves for industrial standard MOSFETs, but when I make my own I get very strange results. My MOSFETs are made on silicon wafers with an SiO2 surface dielectric that is 25 nm - 25 um thick. I have been trying to use P3HT as a standard, where the P3HT layer is spin-cast from a 2% by weight solution (chlorobenzene as the solvent) and is about 200 nm thick. I then deposit 100 nm Ag electrodes in a vacuum chamber. The devices are about 10 mm wide, about 2 mm long, and have a channel length of about 0.5 mm. To make contacts I am using pins on micro-positioners that are connected directly to the keithley system. I make contact to the source and drain, and then I scratch the silicon wafer down to the silicon and make my gate contact where I scratch. When I sweep the drain voltage to, say, -30 V I get a drain current that looks somewhat diodic. As I ramp up the gate voltage to, say, -30 V I don't see any gate activity. The curves are reproduced at all gate-voltages. I know that most organic MOSFETs in research labs are pushed up to +/- 100 V on both the drain and the gate, but mine don't show any activity at these high voltages. Again, I get normal output characteristics on industry MOSFETs, but my own don't work. Any suggestions on:
1-What is a good organic material to use as a standard?
2-What device architecture should I be using?
3-Is it OK to use needles as contacts to such large devices? I am thinking I may need to make the switch to larger, blunt contact pins.
4-Are there any good resources on setting up and standardizing MOSFET measurement systems? I have scoured the web and can't find anything.
Thank you for your help.
