Capacitance techniques are used to show that the dielectric constant ε || of GaN in the kHz frequency range is 10.6 ± 0.3. The data allow depth information to be accurately extracted using methods such as mercury probe capacitance profiling. The measurements complement the pre-existing data which are derived from infrared reflectivity and which give a value of 10.4 ± 0.3.
We have embedded an AlGaAs/GaAs based, gated two-dimensional (2D) hole system (2DHS) into an impedance transformer LC circuit and show that by using radio-frequency reflectometry it is possible to perform sensitive, large bandwidth, electrical resistance measurements of 2D systems at millikelvin temperatures. We construct a simple lumped element model where the gated 2DHS is described as a resistive transmission line. The model gives a qualitative understanding of the experimental results. As an example, we use our method to map out the Landau level evolution in a 2DHS as a function of magnetic field and gate voltage.
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