Control of interface abruptness of polar MgZnO/ZnO quantum wells grown by pulsed laser deposition

A strong quantum confined Stark effect (QCSE) was observed in wedge shaped MgZnO/ZnO quantum wells (QWs) grown by pulsed laser deposition. A reduced laser fluence of 1.8 J/cm(2) was used. Reference samples grown at higher standard fluence 2.4 J/cm(2) showed only a negligible QCSE. Using off-axis deposition without substrate rotation, a constant composition of the barriers was maintained while varying the well width in a wedge shaped QW. A redshift of the QW luminescence with increasing QW thickness up to 230 meV below the ZnO emission was found, accompanied by an increase in the exciton lifetime from 0.3 ns up to 4.2 mu s. (C) 2010 American Institute of Physics. [doi:10.1063/1.3475402]