Near-infrared intersubband absorption in(CdS/ZnSe)/BeTe novel II-VI heterostructures grown bymolecular beam epitaxy

摘要

We report on near-infrared intersubband (ISB) absorption in(CdS/ZnSe)/BeTe quantum wells (QWs) structures, which were grown bymolecular-beam epitaxy. The highly n-type well-doped QW samples wereobtained successfully by introducing a few monolayer CdS into aZnSe/BeTe QW. We have observed ISB absorption with peak wavelengthas short as 1.62 mm, covering 1.55 mm within absorption bandwidth. TheISB carrier relaxation has been also investigated by means of femtosecond(~150 fs) one-colour pump and probe technique at the ISB absorptionpeak. The ISB carrier relaxation time of 270 fs was observed in thesample with the absorption peak at 1.82 mm. The slow decay componentwith a time constant of a few ps, which has been observed in ZnSe/BeTeQWs, was not observed in the (CdS/ZnSe)/BeTe QWs, indicating that theG(ZnSe)-X(BeTe) electron transfer is suppressed as expected from theband alignment.