NONUNIFORM RESONANT COUPLING EFFECT ON 2D ELECTRON-TRANSPORT IN DELTA-DOPED DOUBLE-QUANTUM-WELL STRUCTURES

Effects of resonant coupling on 2D electron transport, especially the wavefunction-dependent scattering of electrons, have been studied in n ovel double quantum well (DQW) field effect structures in which a shee t of ionized donors is inserted in one of the wells. When the two rele vant wavefunctions are modulated by a gate voltage V(g) from localized ones to those extending over both wells, the channel resistance R sho ws a resonant increase, resulting in a peak-to-valley ratio of 2.5 in R-V(g) characteristics at 1.5 K. Magnetic-field dependence of the chan nel resistivity has been investigated to elucidate features of resonan t coupling at two different donor concentrations N(delta). It has been found that the formation of coupled wavefunctions takes place uniform ly only in the sample with low N(delta), whereas the resonant coupling in the sample with high N(delta) (> 10(15) m-2) becomes substantially non-uniform or position dependent in the channel and leads to incompl ete delocalization of wavefunctions.