Nonlinear dynamics of non-equilibrium holes in p-type modulation-doped GaInNAs/GaAs quantum wells
1 School of Computer Science and Electronic Engineering, University of Essex, CO4 3SQ, Colchester, UK
2 Tyndall National Institute, University College Cork, Cork, Ireland
3 Department of Micro and Nanosciences, Helsinki University of Technology, P.O. Box 3500 FI-02015 TKK, Finland
Nanoscale Research Letters 2011, 6:191 doi:10.1186/1556-276X-6-191Published: 2 March 2011
Nonlinear charge transport parallel to the layers of p-modulation-doped GaInNAs/GaAs quantum wells (QWs) is studied both theoretically and experimentally. Experimental results show that at low temperature, T = 13 K, the presence of an applied electric field of about 6 kV/cm leads to the heating of the high mobility holes in the GaInNAs QWs, and their real-space transfer (RST) into the low-mobility GaAs barriers. This results in a negative differential mobility and self-generated oscillatory instabilities in the RST regime. We developed an analytical model based upon the coupled nonlinear dynamics of the real-space hole transfer and of the interface potential barrier controlled by space-charge in the doped GaAs layer. Our simulation results predict dc bias-dependent self-generated current oscillations with frequencies in the high microwave range.