Resonant Tunneling and Its Prospects in Si / ZnS and Si / CaF 2 Heterostructures

The theory of tunneling and resonant tunneling is reviewed. Experimental justification of this theory was provided by an InP-based RTD with room-temperature PVR = 12. Its valley current was well-modeled as the sum of thermionic emission through the second resonance and a temperature-independent scattering/defect component. ZnS and CaF2 were experimentally considered as epitaxial barrier materials for a Si-based RTD. Temperature-dependent J-V measurements were utilized to determine thermionic barrier heights to ZnS. The ZnS/As(1ML)/Si(100) conduction band edge offset and the A1/ZnS(100) barrier height were found to be 1.1±_0.1 and 1.02±0.04 eV, respectively. Al/SiO 2/a-Si/ZnS/As(1ML)/Si(100) doublebarrier devices were fabricated but did not show NDR. Although post-oxidation RTA was performed on this structure, TEM revealed that the Si quantum well did not crystallize. Large current densities through single-barrier Si/CaF2/Si(111) samples and TEM of these samples demonstrated the lack of a quality CaF2 barrier. A working RTD was not fabricated in either of these Si-based materials systems. Thesis Supervisor: Qing Hu Title: Associate Professor of Electrical Engineering and Computer Science