Modern semiconductor optoelectronics research is largely focused on exploiting various advantages that arise upon nanoscale miniaturisation. Progress towards realising exciting associated next-generation technologies (e.g. on-chip optical computing) is primarily driven by advances in nanofabrication coupled with (evolving) material characterisation techniques that provide feedback on performance and quality. Characterisations of spectro-temporal emission in particular yield deep insight into material charge carrier and photon dynamics and are routinely carried out in this research area and beyond. For such measurements, there are a few well-established approaches such as streak camera imaging, that provide a high throughput and high temporal resolution platform. However these devices are expensive, damage sensitive and have limited temporal and spectral ranges. Similarly fluorescence upconversion spectroscopy provides pulse-width limited temporal resolution but operation based on inefficient non-linear optical effects makes it inherently slow and unsuitable for the study of weak emission or rapidly degradable materials. These limitations urgently demand the development of a new approach that is more reliable, simple and inexpensive whilst retaining sufficient spectro-temporal performance. In this PhD research, a novel high-throughput methodology known as interferometric time-correlated single photon counting (i-TCSPC) is demonstrated that combines Fourier transform spectroscopy and traditional TCSPC to obtain ultra-sensitive, broadband simultaneous measurements of time- and spectrally-resolved emission. By folding the emission input of a Michelson interferometer onto two detector channels, spectrally-resolved 2nd order photon correlation measurements are enabled, providing additional applications in the study of non-classical light. Moreover, employing modern TCSPC hardware for the acquisition of âwall-clockâ information facilitates further functionalities suited for kinetics experiments and studies of dynamic behaviours such as fluorescence blinking. i-TCSPC's broad scope of capabilities merits its application in various demanding research fields such as in studies of biological and quantum optical materials. In this presented work, the value of the developed methodology is demonstrated in optoelectronic characterisations of nanowires, quantum wells, perovskite nanocuboids and other nanoscale objects. The i-TCSPC technique proved particularly insightful in the study of novel GaAsP/GaAs quantum well nanowire lasers, leading to the first reported measurement of nanowire laser coherence lengths and revealing a unique nanolasing mechanism that can be exploited to realise state-of-the-art performance. Ultimately i-TCSPC is established as a strong solution, enabling a powerful set of characterisations within a single measurement for a diverse range of applications.
|Date of Award||31 Dec 2020|
- The University of Manchester
|Supervisor||Wendy Flavell (Supervisor) & Patrick Parkinson (Supervisor)|