In Search of Luminescence in Silicon
Final rept. 1 May 95-30 Mar 99
NORTH CAROLINA UNIV AT CHARLOTTE
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Two schemes were studied 1 IAG-Superlattices Interface-Adsorbed-Gas were fabricated in a silicon MBE system capable of exposure to oxygen at 10exp -7 Torr for adsorption. Si deposition is between 5 to 20nm at room temperature with annealing temperature between 800 to 950C, forming 3nm Si nano-particles. Photoluminescence shows two peaks located at 1.7eV and 2.35eV. The former originates from the interior, whereas the latter from the surface regions of the silicon nano-particles. 2 SiO Superlattices were fabricated with silicon epitaxial growth 1.1nm at 550-600C, followed by oxygen adsorption at room temperature. High resolution TEM shows epitaxy, and Plane view TEM shows defect densities, dislocations and stacking faults, below 10exp 9 sq cm. The process is repeated up to 9 periods for photoluminescence, PL, and electroluminescence, EL, measurements. A broad peak located at 1.8eV, originates from quantum confinement in silicon thin layers, and a sharp peak located at 2.2eV, originates from the SiO complexes. EL is particularly impressive. Greenish light output is stable in a life-test of more than one year of continuous operation. Our results stimulate new views toward physical phenomena originated from interfaces and surfaces the overall control and resulting stability allow such devices to be ready for applications.