Profile

I work with a type of materials known as semiconductors, these are very special materials which when very cold behave like an electrical insulator (like wood or rubber), however as they get hotter they behave more like an electrical conductor (like metal wires). The most common type of semiconductor is Silicon, which is used to make all electrical chips and components, however there are many other types of semiconductor materials.

Many of these materials also have a strong relationship with light and I use this effect to design and make lasers and detectors for use in lots of different ways.

To make these devices different semiconductor materials are stacked on top of each other, in a similar way to which you might make a sandwich (the bread is one material, the butter another, and so on). Some of these semiconductor sandwiches can have many different layers (10 – 100) to allow both the light and electricity to be controlled as we want. To then make a laser we put an electrical voltage across the “sandwich” the electrical charges are then converted into light ! The color of the light made is controlled by the semiconductor layer in which it is made (so each material will give off a different color light. These types of lasers are used in lots off applications every day some examples include: DVD Players (Red Lasers), Blue Ray Players (Blue Lasers), Laser Pointers, Medical Testing, and internet fiber optics.

To make a detector from these materials we just operate them the other way round. We shine light on them and this makes an electrical current flow ! – The brighter the light the higher the current that is made, so we can tell how bright an object is. These are commonly use in solar panels and CCD Cameras (like on your mobile phone).

Visible light is just a small section of what is known as electromagnetic radiation. This is a wide range of waves which covers Gamma Rays, X-Rays, Ultraviolet Light, Infrared Light and Radio Waves! So far most of the lasers and detectors that have been made work with visible light, however if we can make lasers that create these other types of radiation (and then detect it again), there are many new uses we can find.

For example if we pass certain colors of infrared light through a person we can see if they have cancer! In the same way we can shine light onto a unknown object and tell what it is – this would be really good in airports as we could then see exactly what was inside each bag.

My days can be quite varied as there are lots of steps involved in making new devices and getting them to be as efficient as possible.

The first stage is to design the devices, this involves computer codes and models so that we can test lots of different idea out to see what looks like it will work – but the computer programs are only as good as our theory !

The next stage involves making the devices! For this I have to go into an special laboratory where everything is ultra clean – this is needed as otherwise we might get dirt or dust on a device which might alter its performance. This means that I have to wear special clothing to help keep things clean

In this lab we put metal onto the devices (so that we can solder wires onto them and connect them to circuits) and use different chemical (Acid!) treatments to change the performance.

We next have to test how good the devices are, for this we have lots of different labs to perform electrical measurements (i.e. applying voltages and currents across the devices) and optical labs where we can see if they work as lasers (or detectors).

We then compare these results to our first computer models to see if we got the result we wanted! If not we have to work out if our models are wrong, or if something went wrong when making the devices.