Modern telecommunications technologies rely on optical data transmission and storage. Keeping pace with this development requires light sources with high modulation rates and low power consumption. Efficient interfaces between optoelectronic devices and common electronics require semiconductor-based light sources. A combination of both is found in semiconductor structures with reduced dimensionality like quantum wells or quantum dots. Placing these as emitters inside microcavities allows for the creation of compact and efficient coherent light sources. This work characterizes several promising candidates for semiconductor low-threshold coherent light emission like quantum dot vertical-cavity surface-emitting lasers on polariton Bose-Einstein condensates in terms of their threshold and coherence properties. Novel techniques to measure their photon statistics with picosecond time resolution are discussed.