A cyclotron-resonance experiment has been performed on various ZnSe crystals with different heat treatments, as a function of magnetic field orientation, temperature, and delay time after photopulse excitation. Two-dimensional (2D) characters of the absorption signal consistently show up for a few samples. X-ray analysis and microscopic observation with polarizers reveal a multimosaic structure of numerous twin-crystal boundaries for these samples. These boundaries evidently lead to a formation of potential wells that are responsible for the 2D character. An experiment with a sample free from boundaries enables us to make a precise determination of the effective-mass value and the temperature dependence of the scattering rate of photoexcited electrons. An extra resonance peak is observed in the experiment with a far-infrared laser. It is interpreted as a polaron-induced nonparabolicity effect of the conduction band in ZnSe. In addition, clear evidence of a two- to three-dimensional transition has been observed.

• Received 23 October 1987

DOI:https://doi.org/10.1103/PhysRevB.37.6153