Sean Muir

Barrier height estimation of asymmetric metal-insulator-metal tunneling diodes

A method is developed to estimate barrier heights of an asymmetric metal-insulator-metal (MIM) diode exhibiting Fowler-Nordheim tunneling. The method requires determination of slopes and intercepts of a log(|I(V+Δϕ)2|) versus 1V+Δϕ plot rather than a log(|I(V)2|) versus 1V plot (i.e., a conventional Fowler-Nordheim plot), where I, V, and Δϕ refer to tunneling current, applied voltage, and the difference in barrier heights, respectively. As the value of Δϕ directly impacts the applied electric field magnitude, it is a critical component in barrier height determination from a current-voltage measurement. Conventional Fowler-Nordheim plot analysis does not employ Δϕ, which compromises the accuracy of barrier height estimation when Δϕ≠0. Using the described method, the barrier heights of a ZrCuNiAl/Al2O3/Al MIM diode are estimated to be 1.75 V and 1.07 V, respectively, and the Al2O3 tunneling effective mass is estimated to be 0.47. Additional MIM diodes are analyzed to show that the accuracy of MIM diode barr...

Synthesis and characterization of Sr{sub 2}Ir{sub 1-x}M{sub x}O{sub 4} (M=Ti, Fe, Co) solid solutions

Abstract The effects of Ti, Fe and Co substitutions for Ir on the structure and on the physical properties of Sr 2 IrO 4 are investigated. A complete solid solution Sr 2 Ir 1− x Ti x O 4 is obtained while both Fe and Co doping are relatively limited. In each case however, the c -axis cell parameter and the initial IrO 6 octahedra tilting decreases with substitution. Doping with Ti, Fe and Co results in a decrease of the magnetic susceptibility and in an increase in the paramagnetic effective moment for Co and Fe doped samples and a suppression of the weak ferromagnetic ordering observed for Sr 2 IrO 4 .