CORDIS - EU research results

Access to the Braun Submicron center for research on semiconductor materials, devices and structures

Final Report Summary - WISSMC (Access to the Braun submicron centre for research on semiconductor materials, devices and structures)

The objective of the WISSMC project was to develop the design of planar microwave detectors on the base of asymmetrically shaped mesoscopic semiconductor structures that can operate in submillimetre wavelength range of electromagnetic radiation:
a) planar diodes with upper contact layer;
b) microwave diodes on the base of 2DEG structures with thinner spacer and the delta-doped layer;
c) gated microwave diodes on the base of 2DEG structures;
d) to develop the design of the microwave diode on the base of thin semiconductor mesa placed onto thin polyimide film;
f) the design of planar microwave diode on the base of GaAs / AlGaAs isotype heterojunction.

The following steps of the implementation of the proposed project were envisaged:
- design of photomasks for the fabrication of planar microwave diodes with 1 mkm dimension of the active part of the diode;
- fabrication of the planar microwave diodes on the base of heterojunction;
- discover a likely regimen of selective etching for removing the substrate;
- semiconductor mesas place onto thin polyimide film;
- electron mobility measurement;
- preliminary testing of the heterojunction diodes in DC regime.

The research team achieved the following:
- calculation of the Tunnelling density of states (TDoS) in a wide range of parameters of system;
- non-monotonic behaviour of TDoS as a function of energy is predicted. The proposal for experiment has been formulated;
- the influence of spin channel on transport through metallic dot has been investigated in the vicinity of Stoner instability point. The magnetic instability manifests itself by strong enhancement in dynamic transverse susceptibility;
- a new method based on an analysis of stochastic equations has been developed for non-perturbative calculations of physical properties of metallic dots in different regimes. This method allows accessing the domain of physical parameters of the system (low temperatures) inaccessible by other methods used for investigation of such systems;
- the analysis of stochastic equations in the vicinity of magnetic instability point shed a light on a physics of mesoscopic grains possessing strong magnetic fluctuations;
- the effective theory of coupled nearly ferromagnetic grains has been developed.