Silicon nanopillars are fabricated by inductively coupled plasma （ICP） dry etching with the cesium chloride （CsCl） islands as masks originally from self-assembly. Wafers with nanopillar texture or planar surface a...Silicon nanopillars are fabricated by inductively coupled plasma （ICP） dry etching with the cesium chloride （CsCl） islands as masks originally from self-assembly. Wafers with nanopillar texture or planar surface are subjected to phosphorus （P） diffusion by liquid dopant source （POCl3） at 870 ℃ to form P-N junctions with a depth of 300 nm. The X-ray photoelectron spectroscopy （XPS） is used to measure the Si 2p core levels of P-N junction wafer with nanopillar texture and planar surface. With a visible light excitation, the P-N junction produces a new electric potential for photoelectric characteristic, which causes the Si 2p core level to have a energy shift compared with the spectrum without the visible light. The energy shift of the Si 2p core level is -0.27 eV for the planar P-N junction and -0.18 eV for the nanopillar one. The difference in Si 2p energy shift is due to more space lattice defects and chemical bond breaks for nanopillar compared with the planar one.展开更多
Tantalum as an insulating barrier can take the place of Al in magnetic tunnel junctions (MTJs). Ta barriers in MTJs were fabricated by natural oxidation. X-ray photoelectron spectroscopy (XPS) was used to characterize...Tantalum as an insulating barrier can take the place of Al in magnetic tunnel junctions (MTJs). Ta barriers in MTJs were fabricated by natural oxidation. X-ray photoelectron spectroscopy (XPS) was used to characterize the oxidation states of Ta barrier. The experimental results show that the chemical state of tantalum is pure Ta^(5+) and the thickness of the oxide is 1.3 nm. The unoxidized Ta in the barrier may chemically reacted with NiFe layer which is usually used in MTJs to form an intermetallic compound, NiTa_2. A magnetic 'dead layer' could be produced in the NiFe/Ta interface. The 'dead layer' is likely to influence the spinning electron transport and the magnetoresistance effect.展开更多
Tantalum as an insulating barrier can take the place of Al in magnetic tunneljunctions (MTJs). Ta barriers in MTJs were fabricated by natural oxidation. X-ray photoelectronspectroscopy (XPS) was used to characterize t...Tantalum as an insulating barrier can take the place of Al in magnetic tunneljunctions (MTJs). Ta barriers in MTJs were fabricated by natural oxidation. X-ray photoelectronspectroscopy (XPS) was used to characterize the oxidation states of Ta barrier. The experimentalresults show that the chemical state of tantalum is pure Ta^(5+) and the thickness of the oxide is1.3 nm. The unoxidized Ta in the barrier may chemically reacted with NiFe layer which is usuallyused in MTJs to form an intermetallic compound, NiTa_2. A magnetic 'dead layer' could be produced inthe NiFe/Ta interface. The 'dead layer' is likely to influence the spinning electron transport andthe magnetoresistance effect.展开更多
基金supported by the National Natural Science Foundation of China(Grant No.50972144)
文摘Silicon nanopillars are fabricated by inductively coupled plasma （ICP） dry etching with the cesium chloride （CsCl） islands as masks originally from self-assembly. Wafers with nanopillar texture or planar surface are subjected to phosphorus （P） diffusion by liquid dopant source （POCl3） at 870 ℃ to form P-N junctions with a depth of 300 nm. The X-ray photoelectron spectroscopy （XPS） is used to measure the Si 2p core levels of P-N junction wafer with nanopillar texture and planar surface. With a visible light excitation, the P-N junction produces a new electric potential for photoelectric characteristic, which causes the Si 2p core level to have a energy shift compared with the spectrum without the visible light. The energy shift of the Si 2p core level is -0.27 eV for the planar P-N junction and -0.18 eV for the nanopillar one. The difference in Si 2p energy shift is due to more space lattice defects and chemical bond breaks for nanopillar compared with the planar one.
文摘Tantalum as an insulating barrier can take the place of Al in magnetic tunnel junctions (MTJs). Ta barriers in MTJs were fabricated by natural oxidation. X-ray photoelectron spectroscopy (XPS) was used to characterize the oxidation states of Ta barrier. The experimental results show that the chemical state of tantalum is pure Ta^(5+) and the thickness of the oxide is 1.3 nm. The unoxidized Ta in the barrier may chemically reacted with NiFe layer which is usually used in MTJs to form an intermetallic compound, NiTa_2. A magnetic 'dead layer' could be produced in the NiFe/Ta interface. The 'dead layer' is likely to influence the spinning electron transport and the magnetoresistance effect.
基金This work was financially supported by the National Natural Science Foundation of China and the Research Foundation for the Doctoral Program of Higher Education of China under Grant No.50271007 and 20030008003, respectively
文摘Tantalum as an insulating barrier can take the place of Al in magnetic tunneljunctions (MTJs). Ta barriers in MTJs were fabricated by natural oxidation. X-ray photoelectronspectroscopy (XPS) was used to characterize the oxidation states of Ta barrier. The experimentalresults show that the chemical state of tantalum is pure Ta^(5+) and the thickness of the oxide is1.3 nm. The unoxidized Ta in the barrier may chemically reacted with NiFe layer which is usuallyused in MTJs to form an intermetallic compound, NiTa_2. A magnetic 'dead layer' could be produced inthe NiFe/Ta interface. The 'dead layer' is likely to influence the spinning electron transport andthe magnetoresistance effect.
