Superconducting contacts to p-InAs

Since no insulating barrier exists between electroplated Pb and the naturally inverted surface channel of p-InAs, this is an attractive system for developing superconductor-semiconductor devices. The electrical and induced superconducting properties of this surface channel have been investigated. A gate-controlled planar Josephson junction further requires that superconductors be separated less than some effective coherence length within the junction barrier. The differential resistance between superconducting Pb contacts on p-InAs has been measured for devices with contact separations down to one μm on substrates with tailored n-type surface conductance. The differential resistance is dependent on the voltage between contacts, magnetic field amplitude and orientation, substrate bias, and temperature. Results show that the Pb superconductivity influences the semiconductor surface transport in a manner which suggests the potential for gate controlled Josephson coupling at realizable contact spacings.