We have investigated optically detected cyclotron resonance (ODCR) and ordinary cyclotron resonance (CR) under the same excitation condition, in Ge, Si and ZnSe, which include both high-purity and doped materials. We have discussed various new features about the impact dissociation process for excitons, bound excitons, bound-multiple-exciton-complex and electron-hole droplets, which are the origin of ODCR. In addition, some information related to hot-electron distribution induced by CR are obtained through the ODCR spectra.