Optical spectroscopy for in situ characterisation of semiconductor interfaces and layers

The potential of optical techniques for semiconductor interfaces and growing layers is demonstrated using in particular the example of Raman spectroscopy in combination with molecular beam epitaxial (MBE) growth. Recent developments allow this method to be applied not only in situ but while growth progresses. This application critically depends on the resonant excitation which provides the required sensitivity for layers in the nanometre range. Here the heteroepitaxy of II–VI compound semiconductors on III–V substrates serves as an example to illustrate the wealth of information, e.g. on layer composition, crystallinity, growth rate, and interfacial reactivity. Very recent results on gallium nitride growth clearly reveal that such experiments can be performed even at temperatures as high as 685?°C.