| dc.description.abstract | In this thesis InAs/Ga(N)As quantum dot intermediate band solar cells (QDIBSCs)
are studied using photoluminescence (PL) spectroscopy. The samples
in this thesis have been complete QD-IBSCs with doping in the substrate,
the emitters and the barrier material.
To the best of my knowledge, this is the first study which attempts to analyse
solar cell structures at this level of complexity. The analysis relies heavily
on the elementary properties previously described by several authors. An
extensive literature survey is included for the reader's benefit.
Due to the high amount of peaks in the initial PL measurements of sample
2-GaAs, the sample was gradually etched by BCl3 down to the substrate.
The peaks turned out to be caused by a software misconfiguration, which
rendered the data unusable for the original purpose.
As a solution, the samples 1-GaNAs, 2-GaAs and 3-GaAs-etched were sent
to Oslo for similar PL measurements. The samples were measured in the
temperature range 10 K to 300 K, for emission wavelengths between 750 nm
and 1500 nm. The GaAs related peaks are composed by several smaller peaks
attributed to the Fermi level (FL), band to acceptor (b-A), donor to acceptor
(D-A) and defect transitions. The QD peaks were located at about 1000 nm
(1.24 eV) and 1100 nm (1.13 eV) for sample 2-GaAs and sample 1-GaNAs,
respectively, due to different QD sizes. From PL intensity and computation
of activation energies, sample 1-GaNAs is likely to contain more defects than
sample 2-GaAs. | en |
