With a high affinity to carbon comparable to titanium and an electrically conductive carbide, zirconium has potential to form ohmic contact on boron doped diamond. In this work, formation of ohmic contacts on boron doped diamond using zirconium is studied in comparison to titanium. Boron doped diamond epitaxial layers have been grown by microwave plasma enhanced chemical vapour deposition with various B/C ratio. Circular Transmission Line Model structures were fabricated using standard micro-fabrication technologies. Specific contact resistance of fabricated contacts was determined for different boron concentrations and for various annealing temperatures. Ohmic contacts using zirconium are formed after annealing at 400 °C. Specific contact resistance steadily decreases with high temperature annealing down to a value of ca. 1 mΩ.cm2 after annealing at 700 °C for highly boron doped diamond. In comparison, titanium contact fabricated on highly doped diamond appears not stable under high temperature annealing.

Lateral conductivity effects have been investigated in self-organised InAs quantum dot (QD) structures grown in a GaAs matrix with different cap layers. Current-voltage (I-V), capacitance-voltage (C-V), DLTS, capacitance and conductance frequency dependence, fast defect transient (FDT), and electron beam induced conductivity (EBIC) measurements were applied. The conductivity in the QD plane decays within a distance of 10 microns. The capacitance transients are dominated by the local QD-plane transversal conductivity and by the free carrier transport in the cap layer. The nonequilibrium free carrier created by electron beam excitation develop a potential barrier at macroscopic distances from the electrical contacts.