Prof Michael Johnston

Abstract:

We have used terahertz spectroscopy to measure the conductivity and time-resolved photoconductivity of a range of semiconducting nanostructures. This article focuses on our recent terahertz conductivity studies on semiconductor nanowires and single walled carbon nanotubes. © 2010 IEEE.

Abstract:

We demonstrate a new scheme for generating THz radiation based on the photo-Dember effect in lateral geometry. By micro-structuring a semiconductor surface we achieve strongly enhanced THz emission comparable to high-efficiency externally biased photoconductive emitters. © 2010 Optical Society of America.

Abstract:

An understanding of aggregation effects in organic semiconductors is essential for their effective use in optoelectronic devices. Typically, the electronic dynamics in such systems are heavily dependant upon the aggregation state, and dynamics often occur on sub-nanosecond timescales. © 2010 IEEE.

Abstract:

We have improved the stability and performance of terahertz photoconductive (Auston) switches using a combination of (NH4)2S surface passivation and silicon nitride (Si3N4) encapsulation. The passivation and encapsulation processes increased the average terahertz power generated four-fold.

Abstract:

We demonstrate a new scheme for generating THz radiation based on the photo-Dember effect in lateral geometry. By micro-structuring a semiconductor surface we achieve strongly enhanced THz emission comparable to high-efficiency externally biased photoconductive emitters. © 2010 Optical Society of America.