Experimental observation of two-dimensional electron gas in the CdS quantum wells of CdS/ZnSe heterostructures

We report the observation of a two-dimensional electron gas (2DEG) in the CdS quantum wells of CdS/ZnSe quantum heterostructures grown by molecular beam epitaxy. The CdS layers are about 4 nm thick; the thicknesses of the ZnSe-doped layers and the growth temperatures of the heterostructures were varied in order to investigate their influence on the 2DEG parameters. The effective sheet concentration of the 2DEGs reached up to 1.5×1013 cm−2. The maximal Hall mobilities were nevertheless still inferior or equal to 380 cm2/V s. Possible scattering mechanisms that cause such low values are discussed. Most probably, it is scattering by stacking faults or by interface roughness.