Semiconductor Materials and Nanostructures

Prof JR Botha has been awarded a Research Chair in Nanophotonics by the Department of Science and Technology (DST). The so-called South African Research Chairs Initiative (SARChI) is one of the key interventions by government in recent years to try and address the critical shortage in research skills in South Africa.

This initiative has five interrelated objectives, namely:

  • to increase the number of world class researchers in South Africa,
  • to retain and/or attract back qualified research scientists to the Higher Education sector and thereby to help reverse the systemic decline in research outputs, focus and capacity at publicly funded higher education institutions (HEIs), Science Councils and other research institutions, and to strengthen and improve the capacity of HEIs, Science Councils, Museums and other research institutions (e.g., University linked Teaching Hospitals) to generate and apply new knowledge,
  • to stimulate strategic research across the knowledge spectrum and thereby increase the level of excellence in research areas of national and international importance,
  • to create research career pathways for highly skilled, high quality young and mid-career researchers that effectively addresses historical racial, gender and age imbalances, and
  • to improve and accelerate the training of highly qualified personnel through research.

Currently, about 87 chairs have been awarded nationally. The Chair in Nanophotonics focuses on the development of optoelectronic materials and structures with dimensions on the nanometer scale. While nanoscience is inherently multidisciplinary, this research endeavour is aimed at consolidating expertise acquired over the past two decades in the Physics Department in the growth and characterisation of semiconductor films, with the specific focus on the development of nanostructures for photonic applications (such as photodetectors, LEDs, laser diodes).

The current programmes are aimed at developing two material systems for photonic applications. Firstly, the department is investigating nanostructures based on the Sb-containing III-V compounds, which provide the flexibility in design to attain operation in the mid- infrared regions. This research is sponsored by the NRF. Device structures manufactured from the Sb-based semiconductor family have the potential to surpass mercury cadmium telluride as the leading material for sensing and emission in the infrared spectral region.

The second material system that forms a research focus is ZnO and the related ternary compound MgZnO. This material system offers an exciting range of optoelectronic applications in the ultraviolet part of the electromagnetic spectrum. One of the main challenges in the successful development of this system for photonic applications is the reliable fabrication of high quality quantum heterostructures (quantum wells, superlattices, nanorods, etc.). Our current research is aimed at optimising the structural, electrical and optical properties of ZnO and MgZnO and achieving p-type material, in order to realise the full benefits offered by band gap engineering in semiconductor structures on the nano and quantum scale.