Heavily doped silicon is required for devices such as PowerMOSFETs. For the devices to be as sufficient as possible it is necessary to lower the electrical resistivity of the silicon substrate as low as possible. Yet, during the growth of heavily n-type doped silicon by the Czochralski method dislocation formation occurs frequently, reducing yield. Thus this work covers the topics intrinsic point defects, electrical activity of dopant atoms, spreading of dislocations and facet growth. Each topic is discussed in regard of their possible impact on the formation of the dislocations. In doing so, the control of facet growth is found to be most crucial to prevent the formation of the dislocations.