At European Microwave Week, state-of-the-art technologies will be to the fore at the conferences and on display at the European Microwave Exhibition. A particular area of interest to the NTT Advanced Technology Corp. is that of GaN-based electronic devices, such as AlGaN/GaN HEMTs, which, because of their material performance, have great potential for the realisation of high power and high frequency devices. In particular, such devices are expected to be applicable for power amplifiers in sophisticated wireless communication systems such as base stations for mobile telecommunications and WiMAX systems.

This is an area that we are currently addressing. Although it is not so easy to grow high quality epitaxial layers for such electronic devices due to the reproducibility limitations of conventional growth techniques we have successfully obtained high-quality GaN-based heterostructure epitaxial layers with good reproducibility using the MOCVD growth technique.

This technique involves using a unique nucleation layer through which a highly resistive GaN buffer layer is realised. The technique also uses a superior quality of InAlN barrier layer that has a higher bandgap energy and a higher sheet carrier density than a conventional AlGaN barrier layer, resulting in high performance HEMT devices. The technique also overcomes the difficulty of growing a high quality InAlN layer without a phase separation.

Such leading edge technologies are the mainstay of European Microwave Week where they can be readily discussed and examined. NTT-AT will show its unique growth technology and exhibit its epitaxial wafer samples on Stand 219.