Direct Optical Energy Gap in Amorphous Silicon Quantum Dots

Abdul-Ameer, Nidhal Mousa; Abdulrida, Moafak Cadim

doi:10.4236/jmp.2011.212185

Cited by 13 publications

(11 citation statements)

References 27 publications

(61 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Silicon, the principal semiconducting material, inherits the indirect optical transitions from its band structure. The research efforts are put forth on realization of light emission effects in silicon-based Si/SiO 2 nanostructured devices exploring hydrogenated amorphous Si [1][2][3][4][5][6][7][8][9], porous Si [10][11][12], Si quantum dots [13][14][15][16][17][18][19], amorphous Si quantum wells (QWs) [20][21][22][23][24], crystalline and nanocrystalline Si QWs [25][26][27][28], and Er-doped QWs [29][30][31]. The fabrication of Si/SiO 2 QWs has been an attractive area in process technology of Si-based light-emitting devices in last few decades.…”

Section: Introductionmentioning

confidence: 99%

Nanostructured Si/SiO2 Quantum Wells

Takeuchi¹,

Horíkoshi²

2019

Nanostructures in Energy Generation, Transmission and Storage

View full text Add to dashboard Cite

The motivation for developing light-emitting devices on an indirect transition semiconductor such as silicon has been widely discussed for Si/SiO 2 nanostructures. In this chapter, we report on the fabrication of Si/SiO 2 quantum-confined amorphous nanostructured films and their optical properties. The Si/SiO 2 nanostructures comprising amorphous Si, SiO 2 , and Si/SiO 2 multilayers are grown using ultrahigh vacuum radio frequency magnetron sputtering. Optical absorption coefficients of the Si/SiO 2 nanostructures are evaluated with regard to tentative integrated Si thicknesses. Optical energy band gaps of the Si/SiO 2 multilayer films are in accordance with the effective mass theory and described as E 0 = 1.61 + 0.75d −2 eV at the Si layer-integrated thicknesses ranging from 0.5 to 6 nm. Quantum confinement effects in the Si/SiO 2 nanostructures are inferred from optical transmittance and reflectance spectra. The rapid-thermal-annealed Si/SiO 2 multilayer films demonstrate the intensified photoluminescence at ~1.45 eV due to the formation of nanocrystalline silicon. The temperature dependence of the nanocrystalline luminescence intensity shows the nonmonotonous behavior which is interpreted invoking the Kapoor model.

show abstract

Section: Introductionmentioning

confidence: 99%

Nanostructured Si/SiO2 Quantum Wells

Takeuchi¹,

Horíkoshi²

2019

Nanostructures in Energy Generation, Transmission and Storage

View full text Add to dashboard Cite

show abstract

“…In this way, TL is one of a large family of luminescence phenomena [1,2]. The light emission from silicon quantum dots is an active research area because of its potential applications in the silicon-based optoelectronic devices [5][6][7][8]. The efficiency of the silicon light emitting devices can be increased with the help of various mechanisms.…”

Section: Introductionmentioning

confidence: 99%

Thermoluminescence from Silicon Quantum Dots in the Two Traps-One Recombination Center Model

et al. 2017

View full text Add to dashboard Cite

A model of the first and general order kinetics describing the thermoluminescence (TL) from silicon quantum dots consisting of two active electron trap levels and one recombination center is proposed. The two trap levels are located at different trap depths beneath the edge of the conduction band. The rate equations corresponding to each trap level allow us to numerically simulate the variation of the concentration of electrons in the two traps and the TL intensity as a function of the temperature for quantum dots 2-8 nm in diameter. It is shown that the intensity increases with decreasing in the dot size, indicating that the quantum confinement effect enhances the radiative recombination rate. The two peaks of the intensity correspond to the two different active electron trap levels. With an increase in the dot size, the peaks of the intensity corresponding to the deepest trap shift to the high temperature region. The variation of the concentration of electrons in the traps is given, and this result bridges the experimental gap, where the TL glow curves are generated, and the variation of the concentration of electrons in traps is unknown.

show abstract

“…The size dependent radiative recombination probability for amorphous silicon (a-Si) quantum dots of radii 1-3 nm is theoretically calculated [5] and summarized in Table I. We adopt this size dependence of radiative recombination probability for our model.…”

Section: Second Order and A Case Beyond Second Order Kineticsmentioning

confidence: 99%

“…TL is a good way to detect the recombination emission caused by detrapping of carriers thermally [5]. TL continues to be an active area of research because of its immense contribution in the fields of personal and environmental dosimetry, dating of archaeological artifacts, sediments and study of defects in solids [1].…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Effect of Retrapping on Thermoluminescence Peak Intensities of Small Amorphous Silicon Quantum Dots

et al. 2016

View full text Add to dashboard Cite

The effect of retrapping on thermoluminescence intensity peak corresponding to each trap of small amorphous silicon quantum dots in three traps -one recombination center model is investigated. For first order kinetics, where there is no effect of retrapping, the thermoluminescence intensity clearly depends on the level of the trap beneath the edge of the conduction band. This energy difference between the edge of the conduction band and the level of the trap is called trap depth (activation energy). The shallowest trap gives the highest thermoluminescence intensity peak for first order kinetics. However, it was clearly observed that for second order and a case beyond second order kinetics, the thermoluminescence intensity peak corresponding to each trap does not depend on the trap depth. In this case, the retrapping probability coefficients are taken into account and most electrons which are detrapped from the shallow trap(s) will be retrapped to the deeper trap(s) resulting in fewer electrons taking part in the recombination process. This significantly reduces the thermoluminescence intensity peaks of the shallower trap(s). It was observed that the deepest trap, with very high concentration of electrons due to the retrapping phenomenon, gives the highest thermoluminescence intensity. In addition, the variation of concentration of electrons in each trap and the intensity of the thermoluminescence are presented. Though we considered the model of three traps and one recombination center, this phenomenon is true for any multiple traps.

show abstract

Direct Optical Energy Gap in Amorphous Silicon Quantum Dots

Cited by 13 publications

References 27 publications

Nanostructured Si/SiO2 Quantum Wells

Nanostructured Si/SiO2 Quantum Wells

Thermoluminescence from Silicon Quantum Dots in the Two Traps-One Recombination Center Model

Effect of Retrapping on Thermoluminescence Peak Intensities of Small Amorphous Silicon Quantum Dots

Contact Info

Product

Resources

About