No abstract

Low temperature luminescence spectra of pure and Sn-doped epitaxial GaAs are reported.

Magnetoreflectance spectra with fine structures of the eightfold 1s-exciton states in CdTe at 6 K in a magnetic field up to 12 T are presented together with a theoretical line-shape analysis. The interactions among the eight components consist of (i) K-linear and quadratic terms, (ii) electron-hole exchange, and (iii) Zeeman and diamagnetic terms. From the calculated line shapes, it is convincingly demonstrated that the K-linear term plays an essential role in (a) producing zero-field anomaly and (b) the appearance of all the eight components at finite fields. From the line-shape fitting, the values of the relevant parameters are determined.

Measurements of the excitation spectra (of the photoluminescence lines below the band gap of CdTe led to the identification of emissions originating from excitons bound to neutral donors, to ionized donors, and to neutral acceptors, as well as from two-electron transitions. Oscillatory variations of the free and bound exciton emission intensity with the energy change of the exciting light above the band gap and their changes with temperature indicated details of the exciton relaxation mechanisms.Mcssungen der Anregnngsspektren der Photolumineszenz von Linien unterhalb der Bandkante von CdTe fiihren zur Tdentifizierung dieser Emissionslinien. Sie werden verursacht durch die Rekombination von Exzit.onen, die an neutrale oder ionisiarte Donatoren oder an neutrale Akzeptoren gebunden sind, sowie von Zwei-Elektronen-Uhergangen. Aus dem oszillatorischen Verhalten der Lumineszenzintensitat von freien und gebundenen Exzitonen bei deran Anregungsspektren oberhalb der Bandkante nnd deren Temperaturabhangigkeit wird auf Einzelheiten der Exzitonen-Relaxationsprozesse gesch!ossen.