Transiente Ladungsträgerdynamik und optische Verstärkung in III-V-Halbleitern
Loading...
Files
Date
relationships.isAuthorOf
Publisher
Philipps-Universität Marburg
item.page.supervisor-of-thesis
Abstract
In this thesis the influences of intrinsic losses on the transient optical gain of the conventional III-V-semiconductor (GaIn)As and the novel dilute nitride (GaIn)(NAs) are investigated for the first time. It is shown that the timescales of the decay of optical gain at room temperature are in both cases comparable. At high excitation densities saturation and feeding processes from higher sub-bands dominate the gain dynamics at transition energies close to the fundamental band gap. In all experiments (GaIn)(NAs) behaves like an ordinary III-V-semiconductor, which shows that this material does not necessitate new concepts for the realisation of efficient lasers besides the optimisation of the growth parameters. Effects on transient optical gain or absorption due to different next-neighbour configurations of the nitrogen are not found. Measurements at high excitation densities show that optical gain can also be observed from higher sub-bands.
In the second part of this thesis the material systems Ga(NPAs) and Ga(NAs) are investigated in respect to their suitability for the realisation of lasers based on GaP substrates. It is demonstrated for the first time that quantum-well heterostructures made of these materials with concentrations of about 3% nitrogen and 8% phophorus show lasing activity from cryogenic temperatures up to room temperature under optical excitation with ultrashort laser pulses. The lasing thresholds at low temperatures are found to be comparable for both material systems. An investigation of the threshold behaviour as a function of temperature reveals a higher characteristic temperature T0 of 86K for the Ga(NPAs) sample compared to 71K for the phosphorus free sample between 20K and room temperature. Measurements of the modal gain for the Ga(NPAs) sample at low temperatures using the Hakki-Paoli method yield values of at least 20/cm.
Finally investigations are made of the decay of differential absorption for diluted nitrides. It is shown that in Ga(NAs) the characteristic lifetimes are reduced by about an order of magnitude from 125ps to about 10ps when the nitrogen contend is increased from 1% to approximately 3%. In a direct comparison indium containing (GaIn)(NAs) samples of similar nitrogen content generally show an increase in the lifetime of the carrier population. This effect is more pronounced at higher nitrogen concentrations (>2%) at which the lifetimes increase by a factor of more than two. Annealing of the (GaIn)(NAs) samples leads to a blue shift of the band gap and to slower decay of the differential signal. In the extreme case a quadruplication of the decay time from 30ps to 115ps is observed at concentrations of 2% nitrogen and 6% indium.
Review
Metadata
Contributors
Supervisor:
Dates
Created: 2006Issued: 2006-09-08Updated: 2011-08-10
Faculty
Fachbereich Physik
Publisher
Philipps-Universität Marburg
Language
ger
Data types
DoctoralThesis
Keywords
Quantum wellsUltrafast phenomenaAnrege-Abfrage-SpektroskopieIII-V semiconductorsSemiconductor laserDilute nitridesPump-probe spectroscopyStimulated emission (see also 42.55.-f Lasers)Transient optical gainTransiente AbsorptionTime-resolved optical spectroscopies and other ultrafast optical measurements in condensed matter (see also 42.65.Re-in nonlinear optics; 82.53.-k Femtochemistry in physical chemistry and chemical ... ... Impurity and defect absorption in solids, see 78.30.-j and 78.40.-q
DFG-subjects
Drei-Fünf-HalbleiterNichtlineare OptikHalbleiterlaserDynamikOptischer GewinnLadungsträgerPhotolumineszenz
DDC-Numbers
530
show more
Borck, Sebastian (132015560): Transiente Ladungsträgerdynamik und optische Verstärkung in III-V-Halbleitern. : Philipps-Universität Marburg 2006-09-08. DOI: https://doi.org/10.17192/z2006.0574.
License
This item has been published with the following license: In Copyright