Semiconductor research receives major Science Foundation Ireland award
6 January 2003

Three researchers at Dublin City University have been awarded a Science Foundation Ireland Principal Investigator grant valued in excess of €1.3 million over four years for their project entitled "ZnO-based material systems for ICT applications".

Dr Jean-Paul Mosnier, Professor Martin Henry and Dr Enda McGlynn are members of the School of Physical Sciences and the National Centre for Plasma Science and Technology, one of DCU's major research centres.

The work which will be undertaken as part of this project will be to develop a novel class of semiconductor material whose properties will be significantly better for use in device applications like laser diodes for data storage on CDs and DVDs, inter alia. Semiconductor materials are at the heart of nearly all optoelectronic devices, such as the lasers diodes used in CD and DVD players, LEDs for lighting and display, optical fibre emitters and receivers used in telecommunications.

ZnO is a semiconductor material that emits light in the blue end of the spectrum (or even the near ultra-violet), as opposed to the normal reddish colour seen from laser diodes used in many applications. The development of laser diodes and LEDs capable of reliably and efficiently emitting blue light is one of the most sought-after goals in optoelectronics technology nowadays. The advantage that such blue light emitters offer is a dramatic increase in the data storage capacity of systems such as CDs and DVDs. The blue light may be focussed to a smaller spot size and hence more "bits" of information can be squeezed into the same area. An increase of a factor of 5 or more in data storage capacity is expected with such blue light emitters. These devices can also operate at high temperature and are immune to visible light interference effects.

There are significant scientific problems in actually making devices based on ZnO. Semiconductors are normally unable to carry an electrical current. In order to make semiconductors useful for devices, it is vital to enable them to conduct electricity. This can be done in two ways, so called n-type and p-type doping, where appropriate elements (e.g. aluminium and nitrogen, n- and p-type dopants respectively) are carefully introduced in the material in minute amounts. By sandwiching together n- and p-type regions in appropriate combinations one makes a whole array of devices, including transistors, LEDs, etc.

While normal semiconductors such as silicon may be doped relatively easily, it is very difficult to dope ZnO p-type, and hence there has been little or no progress in developing working devices based on this material. One of the main aims of this work is to achieve high levels of p-type doping. Our work will be guided by recent theoretical studies of the corresponding mechanism. We will use the technique known as Pulsed Laser Deposition (PLD) to grow ZnO thin films around 200nm thick (approximately five hundredth the width of a human hair), to test these theoretical predictions and to explore new routes towards successful p-type doping. We will thence grow prototype LEDs and laser diodes as device demonstrators.

We will also explore new ways of growing ZnO in tiny wire-like structures (nano-wires) which have a diameter of ~50nm, which will dramatically improve the efficiency of the conversion of electrical energy into light energy.

The research team will include the three principal investigators, Dr Jean-Paul Mosnier, Professor Martin Henry and Dr Enda McGlynn, and a number of postdoctoral and postgraduate researchers.

For further information please contact:

Dr. Jean-Paul Mosnier
Jean-paul.mosnier@dcu.ie
Tel: 01-7005303

Dr. Enda McGlynn
Enda.mcglynn@dcu.ie
Tel: 01-7005387

Professor Martin Henry
Martin.henry@dcu.ie
Tel: 01-7005302