Throwing some light on interface traps

14 06 2011

We’ve been looking to put some more data in preparation for our abstract being accepted for ICSCRM. Chris, one of our third year undergraduate students has been looking at the behaviour of the SiO2/SiC interface under illumination and we sent this off as an abstract. Since then, he’s finished his exams and called in for the day to run some more tests, with a view to understanding the data he took before. The data shows that using sub bandgap illumination, you can photoexcite a trap level in the bandgap, which shows as a second peak in the conductance data.

Conductance trap SiC MOS illumination

Conductance data under illumination

The capacitance data also shows an effect on illumination

Capacitance MOS data trap SiC

Capacitance data under illumination

Whilst none of this data is corrected for the artefacts from the measurement system, it appears that we are causing a big change in DIT with this illumination and the next job is to extract this using the Terman method to find out what we are looking at.

Having photoexcited these traps, we have gone to look at their decay rate, as one of the critical issues in SiC MOS interfaces is the existence of so called ‘slow states’ By looking at the decay of the capacitance and conductance with time, we found that these traps are still releasing carriers some 24 hours after the illumination is removed. It looks like we need to set the system up to run for longer this weekend in the hope that we can get back to the un-illuminated condition!


And suddenly it was June

9 06 2011

Yet another big gap in the timescale of the blog, but now it’s starting to calm down again. So, here is a quick run down of what has happened in the past few days

The good news on my part is that the University agreed my promotion application, so as of the 1st of August I will be the Reader in Semiconductor Technology. I also found out this morning that I have been successfully elected to sit on Senate as of the start of the next academic year. It will be interesting to find out how the University works …

Rupert left us at the end of last month and is now at Dynex Semiconductor in Lincoln, where he is still planning to keep up his work on silicon carbide. It’s his viva in eight days, so fingers crossed and then it’s proud parents day one Saturday in early July.

On the research front it’s been chaotic. We have managed to submit some sixteen conference abstracts in the last month or so, covering topics from negative electron affinity on diamond surfaces to the optical pumping of defects at the SiO2/SiC interface using sub-bandgap illumination. So, it looks like big travel bills as some of us head off to Limerick (IEEE Sensors), Cleveland Ohio (ICSCRM 2011), Oxford (HiTEN) and Warwick (deBeers Diamond conference)

We are also showing off our computational modelling ability at the forthcoming AIMPRO workshop, with the poster below looking at the behaviour of halogenated diamond surfaces.
Diamond Negative electron affinity halogen

And finally, we have an intern studying with us for the next few weeks. Sarah has joined us from Kansas State University for seven weeks and is currently trying to develop high temperature sensors to support dementia suffers in the kitchen Hopefully lots to report on this soon!