Density dependent luminescence properties of CdS/ZnSe single quantum wells

Abstract

PACS 78.47.+p, 78.55.Et, 78.67.De CdS/ZnSe is a quaternary type II system, which allows to tune the luminescence over a considerable fraction of the visible spectrum. We present here theoretical and experimental investigations of the density dependent blue shift of the emission of single quantum wells under cw excitation and on the luminescence dynamics after pulsed excitation as a function of the CdS well width.1 Introduction CdS/ZnSe single and multiple quantum wells (SQW and MQW) and superlattices (SL) form a remarkable, strained, quaternary type II system. The emission can be tuned by a variation of the layer widths from 2.0 eV to 2.7 eV, i.e. over a substantial fraction of the visible spectrum [1,2,3]. The conduction band offset of the CdS wells is with 0.8 eV rather high compared to most of the III-V and II-VI quantum systems. Data on phonons and on intersubband transitions have been presented already in [4,5], partly at preceeding conferences of this series. The some holds for selected aspects of interband transitions [6,7], which show a dependence of the degree of polarization on the termination of the interfaces [2,8]. The influence of localization effects can be deduced e.g. from the non-monotonous dependence of the spectral position and of the FWHM of the emission on temperature. See e.g. [9,10] and for some other material combinations [11]. Here we concentrate on some selected aspects of the emission of CdS/ZnSe SQW in dependence of the CdS well thickness, on cw and pulsed excitation density and on doping.

Electrophysical and cathodoluminescent properties of low‐dimensional CdSSe/CdS structure

“…At RT, lasing appears at λ = 553.5 nm on the shot wavelength edge. Such a shift is typical for the recombination of spatially separated electrons and holes in the type-II heterostructures [5].…”