Investigations into the performance of various HBV physical structures for high efficiency harmonic generation

Heterostructure barrier varactors (HBV) with different physical structures have been investigated and characterised for their capacitance-voltage characteristic and device series resistance. This is a novel concept to increase the HBV capacitance modulation whilst minimize the device series resistance for the NLTL in achieving optimum harmonic generation. Various capacitance modulation characteristics can be engineered by shaping the HBV mesa with either an undercut or side slope on the mesa body without the need to modify the original epilayer properties. This concept greatly improves the quality of the NLTL and essential for broadband harmonic generation which required large amount of NLTL sections for optimum conversion.