Density dependent cyclotron and intersubband resonance in inverted CdTe/HgTe/CdTe quantum wells.

Cyclotron and intersubband resonances in HgTe quantum wells in the inverted band regime are studied by Fourier-transform spectroscopy. Metal-oxide-semiconductor field-effect transistors (MOSFETs) allow us to tune the electron density. In particular, we investigate filling factor dependent splittings of the cyclotron resonance in strong magnetic fields and a crossing of Landau levels of the conduction and valence subband. The experimental results are well described by a 6 × 6 k·p-model

Crossing of Landau levels of conduction and valence subbands in an inverted HgTe/CdTe quantum well

In the inverted-band regime of HgTe/CdTe quantum wells, the lowest Landau level of the lowest conduction subband and the highest Landau level of the topmost valence subband are predicted to cross at a critical magnetic field B$_{c}$. We study this crossing experimentally with far-infrared Fourier-transform spectroscopy in a gated HgTe/CdTe quantum well with tunable electron density. The crossing point is identified by a characteristic exchange of oscillator strength between the two transitions involved, one being a cyclotron resonance, the other an intersubband resonance. The experimental resonance positions, the oscillator strengths as well as the value of B$_{c}$, are in good agreement with theoretical results of a 6 x 6 {\bf k·p} model evaluated for the [211] growth direction

Effect of device processing on 1/f noise in uncooled, auger-suppressed CdHgTe diodes

Auger suppression reduces the leakage current in uncooled CdHgTe diodes to the point where the shot noise limited D* is significantly higher than for other uncooled detectors. However, Auger-suppressed diodes exhibit high levels of 1/f noise and so applications have initially been in devices operating at high frequency such as CO2 laser heterodyne detectors. In order to use Auger suppression in imaging devices, we need to reduce the 1/f noise and this paper describes a study of the effects of device processing on noise. We find that although some of the noise is associated with perimeter leakage currents, variations in the surface passivation treatment have little effect on the total noise. However, a post-passivation anneal can reduce the noise in some cases. We also find that CdTe passivated devices are more stable when baked than those passivated with ZnS