イベント

千現地区 研究本館8階 中セミナー室

Dr. Iain F Crowe
School of Electrical and Electronic Engineering, The University of Manchester

In this contribution, we describe an all-optical (pump-probe) technique for measuring the quantum efficiency (QE) of luminescent materials and, although generally applicable, we apply it as an example to silicon nanocrystals. The technique involves precisely balancing the light leaving a local (mm-scale) region of excitation (by measuring m-PL) with the heat generated at the focused laser spot (by measuring changes in intensity of a near-IR reflected probe). Critically, our optical arrangement (three confocal signals in one microscope objective) combined with an advanced DSP ‘lock-in’ technique, permits measurement of DR/R to within 1 part in 106, corresponding to temperature changes on the mK scale. We present initial data on silicon nanocrystals, formed in glass cover-slips after ion implantation and thermal annealing, and discuss how the technique relates to a true measure of IQE with limitations and how it can be applied more generally to alternative material systems.