19 05 2014

Another question – ‘I was wondering if you could possibly do an example of an example of calculating Pmax for a solar cell please‘.

This one needs a bit more explanation than a one liner – so here goes.  Starting with the circuit schematic for the solar cell with a load resistor, which can be found in figure 11.3



Hence, the current through the load resistor is the photo-current (IL) and a reverse direction p-n junction, which is described by Shockleys equation (see the second year notes!).  This gives equation 11.1.


From this, it is possible to calculate the short circuit current, by setting the voltage term in Shockley’s equation to zero, giving equation 11.3 – but realise that a lot of the terms at the front of the equation are in fact Is – the saturation current!


You can also balance the two currents (IL and the p-n junction) to get Voc (i.e. the voltage when no current flows) and so this gives equation 11.2


Having got all this, the last step is to look at the maximum power.  Because you get zero power at Isc (because V=0) and at Voc (because I=0) there is a voltage and current at which the maximum occurs and this is given by Voc x Isc x FF.  Here the fill factor (FF) is an experimentally extracted value (quoted to you if required)


Research Conference

24 01 2013

Today saw the start of the internal research conference and I’ve been persuaded to give a talk tomorrow. The topic of which is our recent interest, Molybdenum Disulphide. Having spent the afternoon in the cleanroom playing with Scotch tape and trying to make an atomic layer, this is something for the future ?ARC Talk

Omid’s Conference

30 03 2012

In the middle of all the chaos of 2012, Omid has been to present his work on a Novel PWM Generator at the Power and Energy Conference at Illinois (PECI 2012) This was a fantastic success for him, with lots of people really interested in his work, which for the first time enables PWM signals to be generated in hostile environments. This will be a key enabling technology for the realisation of SiC converters for hostile environment and high power applications. On top of all that, he won the prize for the best presentation, a fantastic achievement.

PECI 2012 Winning presentation

Reader freezes balls and electrocutes gherkins …

30 03 2012

A hugely successful day out yesterday, as our roadshow made an appearance at Hetton School. Whilst this is a long day (especially for those of us who don’t teach much) it was fantastic. The kids are so enthusiastic and the teachers are really switched on to the benefits of technology and how it can improve the future.

cryogen engineering exhilarating

Having shown the science (and fun) of liquid cryogens, it was time for the grand finale, where the challenge is for the kids to use their scientific knowledge to make predictions and then understand their observations. Whilst electrocuting gherkins is fun and makes a good spectacle, it does make people realise why they are yellow and tie this into how you can find your way home at night.

Hetton School Gherkin Exhilarating Engineering

Next stop on our grand tour is Bede Academy in Blyth at the end of April!

Upcoming road trips

27 03 2012

As well as the schools visits, I’m off doing two bits of proper science in the coming weeks. Firstly, I have been invited to give a talk at the upcoming NMI workshop on ‘Wide Bandgap Devices in Electronic Systems‘, which is being held at the Manufacturing Technology Centre in Ansty. This will concentrate on the possibilities of Silicon Carbide power electronic systems and will concentrate on our recent work developing a 1kW DC-DC converter as a test bed for our research.
The next opportunity is a presentation at the upcoming ‘Advances in Wireless Sensor Networks for Hostile Environments‘ day, hosted by the Sensors and Instrumentation Network. This is more targeted at our work in signal level devices and the integration challenges for the realisation of a fully functional sensor node for deployment in extreme environments.

As well as these, I’m off to Hetton School on Thursday for more of our ‘Exhilarating Engineering’ roadshow and then hopefully, a holiday to try and enjoy the unseasonal weather we seem to be having.

Extreme Technology hits the road

22 03 2012

There’s lots to update on here from the past few weeks, a lot of which relates to us being out of the office. Since Christmas, Karthik has been to NRL for six weeks, Omid presented his work at the PECI conference (more on that in another post) in Illinois, Ben has returned from his time at Raytheon, Amit was at the diamond conference in Hasselt in Belgium and me, I got as far as North Tyneside!

Exhilarating resilient technology John Spence

Yesterday, I was at John Spence School in North Tyneside enthusing people into the joys of engineering, mostly by showing things that Engineering can do for you, such as electromagnetism and the challenges of really cold things. This was a fun way to follow my last public event, where I was on stage as part of the Bright Club event at the start of Newcastle Science Fest.

Bright Club Science Fest Newcastle

Bright Club is a lot of fun (although I might not have agreed with you five minutes before I went on) where scientists go along and talk about their research in a stand up comedy setting, to a paying audience. Originally devised in London, these have been described by The Guardian as “a ‘thinking person’s’ comedy night”, and by Londonist as “where funny meets brains”. The next one is sometime in June, come along you will be amazed!

ICSCRM 2011 – Day FOUR

16 09 2011

Well  today began with the usual sweet breakfast treats (I now love muffins and bagels…jokes) and as we were joined by Kurt and Nick for breakfast I ditched Lucy as she had some important talks to go to including the first of the day on Phosphorus doped gate oxides in 4H-SiC MOSFETs. While Lucy was hard at work Kurt, Nick and I relaxed whilst discussing American geographical history and Kurt’s experience in driving all the way from east coast to west coast in about three days!

After the mid morning break we attended a few talks on defects and reliability and then spent some time organizing all of the photographs and information we had gathered so far.

At lunch we met some very interesting characters from a range of different backgrounds, which brought up a very opinionated discussion on graphene and its potential in future technologies. Unlike me there were several skeptics present but I think I managed to convince them of its uses.

The afternoon had some very interesting talks for both Lucy and I and it was very refreshing to not have to present any posters! I attended some talks on sensors and LEDs where guys from NASA presented high temperature wire bonding and packaging technologies, which was of great relevance and interest to us. Lucy attended another MOS processing and characterisation session, which was also very useful in many ways particularly the discussion of ways to improve the oxide quality in MOS devices. Options which were discussed both experimental and theoretical investigations into the use of of sodium, rubidium, phosphorus and potassium in gate oxides to improve oxide quality.

The final session of the day was the most important of the week for me as it was 2 hours completely dedicated to Graphene devices and practical applications. The highlights of the afternoon were the talks from  IBM on graphene integrated circuits and a talk from Joshua Robinson on graphene field effect transistors. It is very exciting to be surrounded with so much interest and advancement in the area of graphene and it has definitely motivated me and given me many ideas for my future work in my project.

To top off a good day, the conference banquet was held at the Rock and Roll Hall of Fame by the waterfront in Cleveland. The food was great and we got plenty of time to explore the exhibitions. Once again I also had the opportunity to discuss graphene research with Kurt and Yu-Ming Lin from IBM, which a fabulous opportunity to question some intelligent graphene minds, whilst Lucy pretended to understand the discussions!

I’ll be updating soon with information on the location of ICSCRM 2013 when it is announced at the end of the conference closing plenary.