Photoluminescence of CdGeP2 and (Cd,Mn)GeP2

Photoluminescence of CdGeP, (112) single crystal and CdGeP2 epitaxial film grown on GaAs (001) substrate have been studied and their spectral similarity found. Spectral bands associated with donor/acceptor transitions peak at close energies for both substances and all are lower than the energy gap of the chalcopyrite crystal. On the other hand, the growth of (Cd,Mn)GeP2 ferromagnetic layer on CdGeP2 (112) single crystal was performed to make it possible observation of PL from both the ferromagnetic layer and substrate. The green laser excitation (514, 532 nm) produces a proper photoluminescence similar to that in the undoped CdGeP2 crystal and film. An extra emission from the ferromagnetic-nonmagnetic heterojunction occurs to extend up to photon energies exceeding E-g of the host semiconductor. The short wavelength photoluminescence is to be due to (Cd,Mn)GeP2 dilute magnetic semiconductor (DMS). This fact states that Mn-doped II-IV-V-2 chalcopyrites are closer to II-VI DMS than to another group III-V DMS, where the heavy Mn-doping suppresses photoluminescence at all. Features of the observed short wavelength emission are discussing based on the temperature and spectral analyses. (c) 2005 Elsevier Ltd. All rights reserved.