The metal-insulator transition in the amorphous silicon-nickel system
Amorphous thin films of Si1-yNiy:H have been prepared over a wide range of compositions by radio-frequency sputtering in an argon/hydrogen plasma and their properties studied by various techniques. Transmission electron microscope investigations confirmed that the films were amorphous and the composition of the films was determined by EDAX. The principal object of the study is to investigate the nature of the semiconductor-metal transition in the a-Si1-yNiy:H system. The system has been shown to exhibit a semiconductor-to-metal transition as a function of concentration at approximately y = 0.26 at which value the optical gap shrinks to zero and beyond which the reflectivity falls with increasing photon energy in the region 0.5 - 2 eV, i.e becomes Drude-like. D.C. electrical conductivity measurements as a function of temperature show an increase in conductivity and a decrease in activation energy with increasing nickel content which is close to zero for y 0.26. The optical joint density of states (OJDOS) is finite at all energies for y ~ 0.26, confirming the existence of overlap between the conduction and valence bands. Pressure-induced transitions from semiconductor-to-metallic behaviour of the a-Si1-yNiy:H
Asal, Rasool Abid
The metal-insulator transition in the amorphous silicon-nickel system. Amorphous thin films of Si1-yNiy:H have been prepared over a wide range of compositions by radio-frequency sputtering in an argon/hydrogen plasma and their properties studied by various techniques. Transmission electron microscope investigations confirmed that the films were amorphous and the composition of the films was determined by EDAX. The principal object of the study is to investigate the nature of the semiconductor-metal transition in the a-Si1-yNiy:H system. The system has been shown to exhibit a semiconductor-to-metal transition as a function of concentration at approximately y = 0.26 at which value the optical gap shrinks to zero and beyond which the reflectivity falls with increasing photon energy in the region 0.5 - 2 eV, i.e becomes Drude-like. D.C. electrical conductivity measurements as a function of temperature show an increase in conductivity and a decrease in activation energy with increasing nickel content which is close to zero for y 0.26. The optical joint density of states (OJDOS) is finite at all energies for y ~ 0.26, confirming the existence of overlap between the conduction and valence bands. Pressure-induced transitions from semiconductor-to-metallic behaviour of the a-Si1-yNiy:H
metal transition amorphous system amorphous thin film prepared wide_range composition radio frequency plasma property study various technique transmission electron microscope investigation confirm film amorphous composition film determine principal object study_investigate nature metal transition system system show exhibit metal transition function concentration approximately value optical gap zero beyond fall increase energy region become like electrical measurement function temperature show_increase decrease activation energy increase content close zero optical joint density state finite energy confirm existence overlap valence band pressure induced transition metallic behaviour