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Characterisation of modulation doped quantum dot lasers

Smowton, Peter Michael, Sandall, Ian C., Walker, Craig L., Thomson, John D., Sobiesierski, Angela, Badcock, Tom, Mowbray, David J., Liu, Hui-Yun and Hopkinson, Mark 2006. Characterisation of modulation doped quantum dot lasers. Presented at: Novel In-plane Semiconductor Lasers V, San Jose, CA, USA, 21-26 January 2006. Published in: Mermelstein, C. and Bour, D. P. eds. Novel In-Plane Semiconductor Lasers V. Proceedings of SPIE , vol. 6133. Bellingham, WA: SPIE, 61330T. 10.1117/12.650682

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Abstract

Self-assembled In(Ga)As quantum dot (QD) lasers incorporating p-type modulation doping have generated much interest recently due to reports of a temperature insensitive threshold current and increased modulation bandwidth. The mechanism by which p-type doping improves the performance of QD lasers is thought to be similar to that envisaged for quantum well lasers, where increased gain is expected for a given quasi-Fermi level separation due to a shift in both quasi-Fermi levels towards the valence states. However, the benefits may be much more pronounced in quantum dot structures since the population of the smaller number of dot states can be dramatically affected using relatively low doping levels, which may incur less penalty with regard to increased non-radiative recombination and internal optical mode loss. We present results of direct measurements of the modal gain measured as a function of the quasi-Fermi level separation for samples with different degrees of doping, which demonstrate unambiguously the increased gain that can be obtained at a fixed quasi-Fermi level separation. In addition, we have measured the internal optical mode loss and radiative and non-radiative recombination currents for samples containing 0, 15 and 50 dopant atoms per dot and show that, although the internal optical mode loss is similar for all three samples, the non-radiative recombination current increases for samples containing p-doping. We show that our experimental results are consistent with a simple computer simulation of the operation of our structures.

Item Type: Conference or Workshop Item (Paper)
Date Type: Publication
Status: Published
Schools: Physics and Astronomy
Subjects: Q Science > QC Physics
Publisher: SPIE
ISBN: 9780819461759
ISSN: 0277786X
Related URLs:
Last Modified: 04 Jun 2017 06:24
URI: http://orca.cf.ac.uk/id/eprint/59535

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