An efficient and on-demand source of entangled photons is a requirement for many protocols in the growing field of quantum information. Traditionally, entangled photons are created by parametric down-conversion or similar techniques, which suffer from a low efficiency and a highly stochastic creation time. An alternative method has been proposed and experimentally attempted, using the biexciton cascade recombination, where a biexciton in a semiconductor quantum dot (QD) recombines via one of two intermediate exciton states under the emission of an entangled photon pair. In this talk, the main idea of this method will be presented, as well as some of the challenges due to the degradation of the entanglement caused by the exciton fine structure splitting (FSS) hω. Special attention will be given to understanding the origin of the FSS, and its dependence on the structure of the QD. Finally, methods of eliminating the FSS using electric [1] and magnetic fields will be theoretically analyzed and discussed.