Publications (2)9.54 Total impact
-
Article: Anomalous coulomb drag in electron-hole bilayers.
[show abstract] [hide abstract]
ABSTRACT: We report Coulomb drag measurements on GaAs-AlGaAs electron-hole bilayers. The two layers are separated by a 10 or 25 nm barrier. Below T approximately 1 K we find two features that a Fermi-liquid picture cannot explain. First, the drag on the hole layer shows an upturn, which may be followed by a downturn. Second, the effect is either absent or much weaker in the electron layer, even though the measurements are within the linear response regime. Correlated phases have been anticipated in these, but surprisingly, the experimental results appear to contradict Onsager's reciprocity theorem.Physical Review Letters 01/2009; 101(24):246801. · 7.37 Impact Factor -
Article: Patterned backgating using single-sided mask aligners: Application to density-matched electron-hole bilayers
[show abstract] [hide abstract]
ABSTRACT: We report our work on fabricating lithographically aligned patterned backgates on thin (50–60 μ m ) III-V semiconductor samples using single sided mask aligners only. Along with this we also present a way to photograph both sides of a thin patterned chip using inexpensive infrared light emitting diodes and an inexpensive (consumer) digital camera. A robust method of contacting both sides of a sample using an ultrasonic bonder is described. In addition we present a mathematical model to analyze the variation in the electrochemical potential through the doped layers and heterojunctions that are normally present in most GaAs based devices. We utilize the technique and the estimates from our model to fabricate an electron-hole bilayer device in which each layer is separately contacted and has tunable densities. The electron and hole layers are separated by barriers either 25 or 15 nm wide. In both cases, the densities can be matched by using appropriate bias voltages.Journal of Applied Physics 01/2009; · 2.17 Impact Factor
