OBSERVATION OF A 2-DIMENSIONAL ELECTRON-GAS IN MODULATION-DOPED ZNTE CDSE QUANTUM-WELLS/

We demonstrate the formation of a two-dimensional electron gas in latt ice-matched, modulation-doped ZnTe/CdSe quantum well structures. Despi te the well-known difficulty in n doping the II-VI semiconductor ZnTe, we find that the unusual type-II band alignment between ZnTe and CdSe allows the efficient transfer of free carriers from n-ZnTe into a CdS e quantum well since the deep donor levels in the n-ZnTe barrier lie a bove the confined ground state in the CdSe well. The sizeable well dep th (similar to 1.35 eV) enables the fabrication of two-dimensional ele ctron gases with sheet concentrations up to similar to 6x10(12) cm(-2) , and with a low-temperature mobility up to 1.4 x 10(4) cm(2)/V s. (C) 1998 American Institute of Physics.