"Thank goodness, nothing is perfect" by Dr Carol Trager-Cowan

I am very happy that nothing is perfect, as this has kept me busy for more years than I care to remember. My research has revolved around defects in synthetic crystals grown to make devices ranging from high-power lasers, to LEDs for lighting, to transistors for electric cars.

Defects can be crucial to the operation of a device, e.g., adding chromium impurities to sapphire produces ruby and leads to lasing in ruby lasers; adding impurities to semiconductors is crucial to the production of LEDs. However, where the arrangement of atoms “goes awry”, forming what are referred to as extended structural defects, this can significantly impede a device’s performance, leading to the generation of heat instead of light in an LED for example.

My present research is driven by the need for rapid, non-destructive techniques to reveal and analyse crystal structure, defects and strain in crystalline materials, in particular in III-nitride semiconductor thin films. III-nitride materials are presently the basis of a fast-growing, multi-billion-pound solid-state lighting industry and commercial nitride-based electronic devices are now in use in chargers for phones and laptops; cell phone base stations; satellite communication systems and cable television networks.

Myself and colleagues exploit the diffraction of electrons in crystals to map crystal structure, detect and identify defects and map orientation and strain on the nanoscale. We develop and apply the novel scanning electron microscope techniques of electron backscatter diffraction and electron channelling contrast imaging to “see” defects and changes in orientation and strain to support rapid optimisation of next-generation semiconductor devices.

Host or Publisher Strathclyde Physics Society