Structural Investigations in Nitride Semiconductors for Optoelectronic Applications

The nitride semiconducting materials are stable in the hexagonal wurtzite structure; they exhibit the largest extension of direct band gaps for one alloy family (AlN: 6.2 eV, GaN: 3.5, InN: 0.65), thus are able to cover from the UV to IR wavelength for emission and detection applications. They are obtained as thin layers mainly grown on foreign substrates. As these materials are expected to exhibit high thermal and mechanical stability in addition to the interesting electronic properties, they are due to find applications as high power high frequency components. However, the active parts are made of alloyed heterostructures, and the three compounds exhibit highly distinct physical properties. Therefore the assistance of structural investigations to the fabrication of the devices has been proven to be indispensable. In this work, we report part of our extensive investigations of the growth defects using transmission electron microscopy and theoretical modelling.