Semiconductor photonic devices, for example, laser diodes (LDs), light emitting diodes (LEDs) [1], and photodiodes (PDs) [2,3] have many applications in telecom, medicine, and manufacturing industries. The advantages of these devices over alternative solutions include a compact device structure, low cost, high reliability, and ease of use. The modelling of the flow of current in LDs, LEDs, and PDs is essential for gaining an insight into the main physical processes that govern their operation, and also for the purpose of device optimisation and design.