Rob Mckenna

'Ein Stein und Laser'

I completed my Honours year in 2005 entirely on exchange at the

Technical University Berlin (TUB). My research involved investigating

the photoluminescence (PL) and phototransmission (PT) properties of

numerous wide band-gap semiconductor samples (GaAs, GaN, ZnO) submerged

in liquid nitrogen and liquid helium in non-magnetic and magnetic

cryostats (up to 5 tesla).  The samples were excited using HeCd and

argon ion lasers as well as sodium lamps.  The PL and PT signals provide

considerable information about the electronic structure of the material

and this information is refined through the use of magnetic fields at

low temperatures.

The final focus of my research was on lithium doped ZnO (Li:ZnO) in the

hope of fabricating p-type ZnO. ZnO resists p-type doping, which is the

final hurdle for numerous useful applications, such as: transparent

solar cells for windows, dilute magnetic semiconductors for use in

spintronic applications, highly efficient high-density information

transfer devices and white LEDs. Although my results were inconclusive

for the p-type nature of the Li:ZnO, other results provided a clear

answer for a 40 year old question on the symmetry of the upper valence

band. Being part of a large research group in TUB, I witnessed a number of other very interesting discoveries.

The Honours year took me from being an assignment/poster/exam finishing

machine to being a Physicist. I would definitely recommend it to anyone

(especially the exchange aspect, which gave me experiences well beyond

that of the typical Honours year) and my only advice would be: research

your area well and early, it makes it far more interesting and fruitful,

as well as making it easier at the end. If you'd like to ask me

questions about the Honours year or about exchange, you can contact me

on mckenna_rj@yahoo.com.au.