Magnetoresistance in Dilute $p$-Si/SiGe in Parallel and Tilted Magnetic Fields (2009)
Drichko, I. L., Smirnov, I. Yu., Suslov, A. V., Mironov, O. A., Leadley, D. R.
We report the results of an experimental study of the magnetoresistance $\rho_{xx}$ and $\rho_{xy}$ in two samples of $p$-Si/SiGe with low carrier concentrations $p$=8.2$\times10^{10}$ cm$^{-2}$ and...
Myranov, Maksym, Leadley, D. R. (David R.), Shiraki, Y.
Epitaxial growth of a compressively strained Ge quantum well (QW) on an ultrathin, 345 nm thick, Si0.4Ge0.6/LT-Si0.4Ge0.6/Si(001) virtual substrate (VS) has been demonstrated. The VS, grown with a...
Reverse graded relaxed buffers for high Ge content SiGe virtual substrates (2008)
Shah, V. A. (Vishal A.), Dobbie, A. (Andy), Myranov, Maksym, Fulgoni, D. J. F., Nash, L. J., Leadley, D. R. (David R.)
An innovative approach is proposed for epitaxial growth of high Ge content, relaxed Si1−xGex buffer layers on a Si(001) substrate. The advantages of the technique are demonstrated by growing such...
Relaxation of strained silicon on Si0.5Ge0.5 virtual substrates (2008)
Morris, R. J. H. (Richard J. H.), Leadley, D. R. (David R.), Parker, Evan H. C., Fulgoni, D. J. F., Nash, L. J.
Strain relaxation has been studied in tensile strained silicon layers grown on Si0.5Ge0.5 virtual substrates, for layers many times the critical thickness, using high resolution x-ray diffraction....
Studies of Skyrmions at ν=1 in the Limit of Zero g-factor. (2008)
D. R. Leadley, R. J. Nicholas, D. K. Maude, A. N. Utjuzh, J. C. Portal, J. J. Harris, ...
In a two-dimensional electron gas at ν=1 (where the filling factor ν=neh/eB measures how many Landau levels (LL) are filled) the ground state should be regarded as a ferromagnet since all the spin...
FRACTIONAL QUANTUM HALL EFFECT MEASURED IN A SPIN DEGENERATE ELECTRON GAS (2008)
D. R. Leadley, R. J. Nicholas, D. K. Maude, J. C. Portal, J. J. Harris
The influence of spin on the Fractional Quantum Hall Effect is investigated in GaAs-GaAlAs heterojunctions in a filling factor region where both spin states of the lowest Landau level are occupied....
The dependence of the Composite Fermion effective mass on carrier density and Zeeman energy (2008)
R J Nicholas, D R Leadley, M S Daly, P Gee, J Singleton, ...
Abstract. Measurements of the temperature-dependent resistivity of high-mobility GaAs/GaAlAs heterojunctions are used to measure the effective mass of Composite Fermions (CF). The CF effective mass...
Measurements of composite Skyrmions at filling factor 1/3 (2008)
D. R. Leadley, R. J. Nicholas, D. K. Maude, A. N. Utjuzh, J. C. Portal, J. J. Harris, ...
Measurements of the fractional quantum Hall effect energy gaps at high pressures are presented that provide evidence for the existence of composite Skyrmions. Just as charged spin textures known as...
Beer, C. (Chris), Whall, Terry E., Parker, Evan H. C., Leadley, D. R. (David R.), De Jaeger, Brice, Nicholas, Gareth, ...
Effective mobility measurements have been made at 4.2 K on high performance high-k gated germanium p-type metal-oxide-semiconductor field effect transistors with a range of Ge/gate dielectric...
Drichko, I. L., Dyakonov, A. M., Smirnov, I. Yu., Suslov, A. V., Galperin, Y. M., Vinokur, V., ...
We study DC and AC transport in low-density $p-$Si/SiGe heterostructures at low temperatures and in a broad domain of magnetic fields up to 18 T. Complex AC conductance is determined from...
Critical Collapse of the Exchange Enhanced Spin Splitting in 2-D Systems (2007)
D. R. Leadley, R. J. Nicholas, J. J. Harris, C. T. Foxon
The critical filling factor νc where Shubnikov-de Haas oscillations become spin split is investigated for a set of GaAs-GaAlAs heterojunctions. Finite temperature magnetoresistance measurements are...
Parker, Evan H. C., Leadley, D. R. (David R.), Grasby, T. J., Capewell, A. D.
Relaxation of strained silicon on 20% linear graded virtual substrates was quantified using high resolution x-ray diffraction and a defect etching technique. The thickness of strained silicon was...
Drichko, I. L., Diakonov, A. M., Smirnov, I. Yu., Andrianov, G. O., Mironov, O. A., Myronov, M., ...
The interaction of surface acoustic waves (SAW) with $p$-type Si/Si$_{0.87}$Ge$_{0.13}$ heterostructures has been studied for SAW frequencies of 30-300 MHz. For temperatures in the range 0.7$
Surface Acoustic Waves probe of the p-type Si/SiGe heterostructures (2004)
Andrianov, G. O., Drichko, I. L., Diakonov, A. M., Smirnov, I. Yu., Mironov, O. A., Myronov, M., ...
The surface acoustic wave (SAWs) attenuation coefficient $\Gamma$ and the velocity change $\Delta V /V$ were measured for $p$-type Si/SiGe heterostructures in the temperature range 0.7 - 1.6 K as a...
Application of Bryan's algorithm to the mobility spectrum analysis of semiconductor devices (2003)
Chrastina, D., Hague, J. P., Leadley, D. R.
A powerful method for mobility spectrum analysis is presented, based on Bryan's maximum entropy algorithm. The Bayesian analysis central to Bryan's algorithm ensures that we avoid overfitting of...
Searches for Skyrmions in the Limit of Zero g-Factor (1998)
Leadley, D. R., Nicholas, R. J., Maude, D. K., Utjuzh, A. N., Portal, J. C., Harris, J. J., ...
Energy gaps have been measured for the ferromagnetic quantum Hall effect states at v=1 and 3 in GaAs/GaAlAs heterojunctions as a function of Zeeman energy, which is reduced to zero by applying...
Critical Collapse of the Exchange Enhanced Spin Splitting in 2-D Systems (1998)
Leadley, D. R., Nicholas, R. J., Harris, J. J., Foxon, C. T.
The critical filling factor v_c where Shubnikov-de Haas oscillations become spin split is investigated for a set of GaAs-GaAlAs heterojunctions. Finite temperature magnetoresistance measurements are...
Searches for skyrmions in the limit of zero g-factor. (1998)
Leadley, D. R., Nicholas, R. J., Maude, D. K., Utjuzh, A. N., Portal, J. C., Harris, J. J., ...
Measurement of composite skyrmions at filling factor 1/3. (1998)
Leadley, D. R., Nicholas, R. J., Maude, D. K., Utjuzh, A. N., Portal, J. C., Harris, J. J., ...
Skyrmions and composite fermions in the limit of vanishing Zeeman energy (1998)
R J Nicholas, D R Leadley, D K Maude, J C Portal, J J Harris, C T Foxon
Abstract. We describe the properties of a strongly interacting two-dimensional (2D) electron gas in high magnetic fields whose properties can be described in terms of the formation of composite...
Searches for skyrmions in the limit of zero g-factor (1998)
D R Leadley, R J Nicholas, D K Maude, A N Utjuzh, J C Portal, J J Harris, ...
Abstract. Energy gaps have been measured for the ferromagnetic quantum Hall effect states at ν = 1 and 3 in GaAs/Ga0.7Al0.3As heterojunctions as a function of Zeeman energy, which is reduced to zero...
Fractional Quantum Hall Effect Measurements at Zero g-Factor (1997)
Leadley, D. R., Nicholas, R. J., Maude, D. K., Utjuzh, A. N., Portal, J. C., Harris, J. J., ...
Fractional quantum Hall effect energy gaps have been measured in GaAs/GaAlAs heterojunctions as a function of Zeeman energy, which is varied by applying hydrostatic pressure up to 20 kbar. The gap at...
Pulsed Magnetic Field Measurements of the Composite Fermion Effective Mass (1995)
Leadley, D. R., Nicholas, R. J., Foxon, C. T., Harris, J. J.
Magnetotransport measurements of Composite Fermions (CF) are reported in 50 T pulsed magnetic fields. The CF effective mass is found to increase approximately linearly with the effective field $B^*$,...