抄録
Offer Organization: Japan Society for the Promotion of Science, System Name: Grants-in-Aid for Scientific Research, Category: Grant-in-Aid for Scientific Research (C), Fund Type: -, Overall Grant Amount: - (direct: 2300000, indirect: -)
Er ions doped in Si nanometer-sized materials give rise to intense 1.54mum emission at room temperature. The motivation of this study is to apply the Er-doped nanocrystalline Si to new optical devices and memories. Main results of this project are shown in bellow.
(1).Size control of Si nanocrystallites by using Eras a nucleation center
Size control of Si nanocrystallites formed in n-Si matrix is achieved by using Er as a nucleation center. We have fabricated a series of nc-Si samples with size from 3 nm to 10 am. The smallest crystallite size was 2.7 nm. a Si dot including -1000 atoms. The nc-Si layers are homogeneous both in the crystallite size and in the optoelectronic properties. The samples show a blue emission band and a sharp peak at 1.54mum up to room temperature. We showed that the blue emission shift to higher energies with decreasing size which is in good agreement with the absorption data and could be explained by a novel quantum size effect.
(2).Room-temperature 1.54 mum emission from Er-doped porous Si
Er was doped into porous Si by immersing the porous Si sample in a saturated ErCl_3 : ethanol solution. Sharp and intense 1.54 mum photoluminescence caused by intra-4f-shell transitions in Er^<3+> ions was observed up to room temperature. Time resolved study of the Er-doped porous Si revealed that the doped Er^<3+> ions were excited by energy transfer from electron-hole pairs in the host. The energy back transfer process is not a dominant factor to quench the Er-related emission in porous Si. A probe effect of measuring the absorption edge of the host by Er emission was proved both for porous Si and nc-Si. Our results were well explained by a proposed model in which an intermediate state was introduced.
(3).An Er-doped nc-Si laser operated at room temperature
Er-doped nc-Si waveguides were fabricated on Si substrates. A stimulated emission at 1.54 mum was demonstrated at room temperature. The sizes of the fabricated Er-doped nc-Si waveguides were 5000 nm x 200 nm x L, where L is the cavity length and is changed from 1 mm to 10 mm. This is the first breakthrough of realizing an all-Si laser.