1998 Fiscal Year Final Research Report Summary
Visible Luminescence Process in Silicon Materials
| Project/Area Number |
09650068
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Applied physics, general
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| Research Institution | Nihon University |
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Principal Investigator |
MURAYAMA Kazuro Nihon University, College of Humanities & Sciences, Professor, 文理学部, 教授 (70107697)
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| Project Period (FY) |
1997 – 1998
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| Keywords | Porous Silicon / Amorphous Silicon / Quantum Confinement / Nanoparticle / Stokes shift / Luminescence |
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| Research Abstract |
The evolution of a red luminescence spectrum of porous Si to the excitation energy has suggested that Si nanoparticles in the porous Si are discriminated into red-luminescent Si nanoparticles with bandgaps larger than 1.5 eV and red-nonluminescent ones with the smaller bandgaps. The evolution has shown that the luminescence peak energy EL of the porous Si nanoparticle is related to the bandgap Egby EL=0.65Eg+0.44 (eV). The relation has been explained from the model that holes in the Si nanoparticles excited by the interband excitation are trapped and then radiatively recombine with electrons in the conduction band.
The fundamental absorption edge spectra of ultrathin a-Si : H films with thicknesses of 400, 50, 25, 13 and 5 A in a-Si : H/a-Si_3N_4 : H multilayers have been determined over the absorption coefficient range from 10 to 10^6 cm^<-1> from the optical transmission and luminescence excitation spectra. The obtained spectra show that the extended states of the bulk a-Si : H exhibit an energy shift due to the quantumconfinement in the a-Si : H well layer while the localizedband tail states exhibit no significant energy shift. Excitation energy dependence of the peak energy of the luminescence has shown that the thermalization gapof the a-Si : H well layer increases with decreasing well layer thickness in thewell layers thinner than50 A and the luminescence in a-Si : H has the Stokes shiftof0.4 eV.
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