Electron and Hole<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi mathvariant="italic">g</mml:mi></mml:math>Factors and Exchange Interaction from Studies of the Exciton Fine Structure in<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mrow><mml:mi>In</mml:mi></mml:mrow><mml:mrow><mml:mn>0.60</mml:mn></mml:mrow></mml:msub></mml:mrow><mml:mrow><mml:msub><mml:mrow><mml:mi>Ga</mml:mi></mml:mrow><mml:mrow><mml:mn>0.40</mml:mn></mml:mrow></mml:msub></mml:mrow><mml:mi>As</mml:mi></mml:math>Quantum Dots

Self-assembled ${\mathrm{In}}_{0.60}{\mathrm{Ga}}_{0.40}\mathrm{As}$ quantum dots (QD's) have been studied by single dot magnetophotoluminescence spectroscopy ( $B\ensuremath{\le}8\mathrm{T}$). At $B\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}0$ a splitting of the exciton ( $X$) emission is observed which we ascribe to an asymmetry of the confinement potential. With increasing $B$ the emission splits into a quadruplet corresponding to the $m\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}\ifmmode\pm\else\textpm\fi{}2$ and $\ifmmode\pm\else\textpm\fi{}1X$ states, which originates from a reduction of the cubic symmetry of the QD's. From the spectroscopic data we obtain values for the electron ( $e$) and hole ( $h$) $g$ factors. We also determine the $X$ singlet-triplet splitting which is found to be enhanced over bulk values by about an order of magnitude due to the increase of the $e\ensuremath{-}h$ overlap in the QD's.