Electrical and optical properties of the CdS quantum wells of CdS/ZnSe heterostructures

Earlier we reported the investigation of the electrical properties of selectively doped and degenerate CdS/ZnSe quantum heterostructures grown by molecular beam epitaxy [V. Kazukauskas, M. Grun, St. Petillon, A. Storzum, and C. Klingshirn, Appl. Phys. Lett. 74, 395 (1999)]. The maximum Hall mobilities in these heterostructures were found to be less than 400 cm(2)/Vs. In the present work we analyze in detail the scattering mechanisms in order to increase the carrier mobility and to optimize these quantum structures. We demonstrate that the Hall mobility can reach in the CdS quantum wells at low temperatures 2800 cm(2)/V s for slightly doped structures, having an effective sheet carrier density 2.6x10(11) cm(-2). In these structures the mobility is mostly limited by interface alloying scattering. At high doping levels carriers become redistributed between the quantum well and the ZnSe doped layer. This causes the parallel conductivity phenomena, which diminishes the effective mobility. Near room temperature the scattering by optical phonons prevails which is superimposed by dislocation scattering. (C) 2003 American Institute of Physics.