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Title: Investigation of 1.55 m GalnNAsSb/GaNAs semiconductor quantum well laser structures
Author: Ferguson, James William
Awarding Body: Cardiff University
Current Institution: Cardiff University
Date of Award: 2010
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A new GaAs based material system capable of emission at 1.55 m is a quantum well of the quinary material GalnNAsSb sandwiched between GaNAs barriers. This material couples 1.55 m emission with the inherent ability of GaAs based devices to be made into VCSELs, making it a very promising solution to being a cheap temperature stable laser material for optical fibre networks. In this work the segmented contact method is used to measure the gain, loss and spontaneous emission (which is then calibrated to give the radiative current density) of this material. These properties are compared for structures with: different levels of doping, different nitrogen contents, different numbers of quantum wells and different barrier widths. The non-radiative current density is compared for the structures with different well numbers and is used to show that the non-radiative recombination in a barrier is equal to that in one well. Further analysis using the simulation program Simwindows shows that this non-radiative current in the barrier is due to Shockley-Reed-Hall recombination (defect recombination). Comparing the non-radiative current for the differently sized barriers and then applying further analysis with Simwindows shows that reducing the barrier size leads to an increase in non-radiative current due to reduced material quality. This then leads to the conclusion that in order for progress to be made with GalnNAsSb active regions the barriers surrounding them need to be changed to GaAsP, or the material quality of GaNAs needs to be greatly improved.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: QC Physics