The growth optimisation and nuclear spinl eddects in Ill-V semiconductor quantum dots are investigated and described in this thesis, The two main methods of epitaxial growt.h (molecular beam epitaxy and metal-orgnic vapour phase epitaxy) are considered, QuantuIIl dot growt h within material system of InP/GaInP is studied. with the effect on the resulting quantum dot charactristics such as spatial and spectral density investigated with respect to growth parameters, This provides an optimised low density of quantum dots for single-dot studies. The nuclear spin behaviour of single quantum dots is investigated through optically- detected nuclear magnetic resonance experiments. A radio frequency electro-magnetic field is applied to the sample during the experiment, and the competition between this route of nuclear spin depolarisation and the nuclear spin polarisation dUE' to an incident flux of spin polarised photons is observed and investigated. The effectivc Knight and Overhauser fields are found and a suitable mathematical model is shown to support the observed phenomena and conclusions, In addition, the effects 011 the emission behaviour of IuGaAs. CuAs and GaAsiAlGaAs quantum dots upon addition of low density dopant atoms such as manganese and iron is t hen studied, It is concluded that such quant um clots doped with single manganese atoms are unlikely to be produced spontaneously in strained material systems but in strain-free material systems an unexpected effect is observed in μPL power dependent emission spectra whereby each line consists of two or three contributions