Contactless tunneling to semiconductors

Abstract

We present current versus voltage characteristics for two metal-insulator-semiconductor systems: lead-insulator-mercury cadmium telluride and silver-insulator-silicon. A previously developed new technique allows us to suspend the metal <20 Å above the semiconductor so that the insulator is simply the space between them. The Si studies at room temperature show features suggestive of electron tunneling between the metal and semiconductor, while the HgCdTe studies in liquid helium conclusively show the Pb superconducting energy gap, demonstrating that contactless tunneling studies of semiconductor surfaces are possible.