Correlation between the physical parameters of the i –nc-Si absorber layer grown by 27.12 MHz plasma with the nc-Si solar cell parameters

Das, Debajyoti; Mondal, Praloy

doi:10.1016/j.apsusc.2017.04.227

Cited by 39 publications

(13 citation statements)

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“…A characteristic HR-TEM image of B-doped nc-SiO X :H prepared at CO 2 = 0.25 sccm, as shown in Figure a, exhibited the crystalline nature of the Si-network wherein the silicon nanocrystals (Si-ncs) of different sizes were distributed over a-SiO X :H matrix. The corresponding electron diffraction pattern, as shown in Figure a(i), demonstrated the prominent presence of the corresponding ⟨111⟩, ⟨220⟩, and ⟨311⟩-oriented crystalline planes of Si-ncs. , Figure a(ii) shows a magnified view of a silicon nanocrystal of ∼5.0 nm diameter and with ⟨220⟩ crystal planes having a lattice spacing of ∼0.19 nm Figure b presents the HR-TEM image of sample B, which did not show any sharp contrast in structures and clearly indicated that no Si nanocrystals (Si-ncs) remained in the film and they were purely amorphous.…”

Section: Results and Discussionmentioning

confidence: 96%

“…29,30 Figure 2a(ii) shows a magnified view of a silicon nanocrystal of ∼5.0 nm diameter and with ⟨220⟩ crystal planes having a lattice spacing of ∼0.19 nm. 31 Figure 2b presents the HR-TEM image of sample B, which did not show any sharp contrast in structures and clearly indicated that no Si nanocrystals (Si-ncs) remained in the film and they were purely amorphous. The corresponding diffraction pattern, as shown in Figure 2b(i), revealed no sharp rings of the crystallographic planes of Si nanocrystals.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

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Complex Dielectric Characteristics, ac-Conductivity, and Impedance Spectroscopy of B-Doped nc-SiO_X:H Thin Films

Das

Samanta

2021

ACS Appl. Electron. Mater.

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Temperature-dependent ac conductivity, impedance spectroscopy, and complex dielectric properties have been investigated on boron-doped silicon oxide (SiO X :H) films grown by radio frequency plasma-enhanced chemical vapor deposition at low temperature (∼250 °C). The two-phase characteristics, e.g., silicon nanocrystals (Si-ncs) embedded in amorphous oxide (a-SiO X :H) tissues, have been evaluated initially by structural studies and subsequently via impedance spectroscopy. Impedance spectroscopy also facilitates identifying the contribution of each individual phase (nanocrystalline and amorphous) on the electronic properties of the materials. The dependence of relaxation time on temperature obeys Arrhenius behavior and also confirms a non-Debye type response under the varying electric field. The negative temperature coefficient of resistance behavior reveals the semiconducting nature of the materials. A designed equivalent circuit model using parallel R∥CPE shows comprehensive correlation among structural, microstructural, and charge carrier characteristics. Frequency-dependent conductivity follows Jonscher’s power law non-linear fitting and reveals a less than unity magnitude of its exponent “n”. The temperature dependence of ac conductance identifies a non-overlapping small polaron tunneling mechanism prevailing in the B-doped SiO X :H network. The tunneling distance is higher in B-doped nc-SiO X :H, and it reduces faster at higher frequency in the B-doped a-SiO X :H matrix. The charge carrier density of states, N(E F), is higher in nc-SiO X :H; however, the lower N(E F) of B-doped a-SiO X :H enhances faster at elevated frequency. The frequency-dependent electrical transport in the B-doped nanocrystalline/amorphous heterostructured SiO X :H network has never been explored before.

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Section: Results and Discussionmentioning

confidence: 96%

Section: ■ Results and Discussionmentioning

confidence: 99%

Complex Dielectric Characteristics, ac-Conductivity, and Impedance Spectroscopy of B-Doped nc-SiO_X:H Thin Films

Das

Samanta

2021

ACS Appl. Electron. Mater.

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“…32 Another component at an intermediate to a-Si and nc-Si, called the ultra-nanocrystalline silicon (unc-Si), exists at 510 cm −1 , and it is considered a part and portion of crystallinity. The following equation was used to compute the total volume fraction of crystallinity (X C ) for each sample 33,34…”

Section: Resultsmentioning

confidence: 99%

“…Another component at an intermediate to a-Si and nc-Si, called the ultra-nanocrystalline silicon (unc-Si), exists at 510 cm –1 , and it is considered a part and portion of crystallinity. The following equation was used to compute the total volume fraction of crystallinity ( X C ) for each sample , where I represent the integrated intensity under each component. In addition, the average grain size of nanocrystals ( D ) for each sample was determined utilizing where β = 2.0 cm –1 nm 2 and Δω signifies the displacement of the nc-Si peak relative to the c-Si peak location, ideally considered at 521 cm –1 .…”

Section: Resultsmentioning

confidence: 99%

Studies on the Impedance Characteristics, Dielectric Relaxation, and ac Conductivity in Silicon Oxycarbide (SiO_xC_y:H) Films at the Amorphous-to-Nanocrystalline Transition Zone

Shyam

Das

2022

ACS Appl. Electron. Mater.

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The impedance characteristics and ac conductivity behavior of the silicon oxy-carbide (SiO x C y :H) network have been investigated during its transition from an amorphous dominated to a crystalline populated structure, grown by varying only the growth temperature (T S) from 160 to 180 °C. At elevated T S, the Si nanocrystals (Si-ncs) increased in size and number density, with corresponding elevation in crystallinity from 28 to 45%. Two distinct dielectric relaxations for the individual a-SiO x C y :H and nc-Si components were identified in the low-frequency and high-frequency zones, respectively, for the film deposited at higher T S (180 °C). In contrast, for the lower T S (160 °C)-grown film, a significant fraction of the ultra-nanocrystalline (unc-Si) component contributed only one consolidated relaxation peak at a moderate frequency. The scaling measurements of the imaginary part of impedance (−Z Im) revealed two distinct physical events for a-SiO x C y :H and nc-Si, both being temperature scale-independent. The activation energy of relaxation is low for the ordered nc-Si component and high for the disordered a-SiO x C y :H matrix. According to the Bode plot analysis, the presence of several defects in the grain boundary contributed a poor carrier lifetime to the nc-Si component, while the a-SiO x C y :H matrix with lesser defects had a longer carrier lifetime. An equivalent circuit model formed by parallel resistors and constant phase elements (R||CPE), following Nyquist plot analysis, demonstrated an intense association between the microstructural and charge carrier characteristics. The temperature-dependent ac-conductivity behavior of the mixed-phase material is well explained by the nonoverlapping small polaron tunneling model, at two individual stages across a transition from an amorphous to crystalline configuration around a small span of growth temperature.

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“…The extrinsic p-doped µc/nc-Si:H thin lms nd important application in window layer of microcrystalline silicon bottom cell of thin-lm tandem ("micromorph") solar cells [5]. P-doped micro/nanocrystalline thin lms have higher transparency property hence this layer could replace silicon carbide p-type window layer in a-Si:H thin-lm solar cells [6]. However, the kinetics of crystallization of a-Si lms have been the focus of research area of many studies deposited by several deposition methods such as sputtering, evaporation, glow discharge, electron beam and ion -implantation has been reported [7][8][9][10][11][12][13][14][15][16][17].…”

Section: Introductionmentioning

confidence: 99%

Boron Induced Crystallization of Silicon on Glass: an Alternate Way to Crystallize Amorphous Silicon Films for Solar Cells

Juneja

Kumar

2022

Silicon

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Demand for e cient window layer in thin lm solar cells with high crystallinity is ever increasing that nds important application in multi-junction/tandem silicon solar cells. Doping of diborane (B 2 H 6 ) in hydrogenated silicon lms using plasma discharge decomposition of silane (SiH 4 ) and (B 2 H 6 ) gases were analyzed. The boron ow (FB) to silane ratio was varied from 0-0.30. Variation in lm characteristics with B 2 H 6 gas-phase ratio were analyzed, and concluded that doping boron induces crystallization in hydrogenated amorphous silicon (a-Si: H) lm structure. The Raman and eld emission scanning electron spectroscopy (FESEM) con rmed the boron induced crystallinity effect in silicon lms at different diborane ow. The results showed that as boron content increases beyond certain ratio, silicon crystallization suppresses and the crystallite sizes were also reduced. From results, it was observed that crystallinity in FB = 0.05 is 79 % and decreases to 77 % when lms are slightly higher doped (FB = 0.10) and further decreases when the lms were heavily doped. These results validate that boron suppresses silicon crystallization due to local deformations caused by the impurities. Infra-red absorption studies and their analysis also con rm the crystallization in boron doped lms with additional band appears at ~ 611 cm − 1 . This band is named as boron induced crystallinity mode of vibrational spectra.The estimated hydrogen content (C H ) decreases con rmed crystallinity in the silicon structure with boron doping. Further, the energy dispersive spectroscopy (EDX) indicates the presence of boron and other impurities in deposited silicon lms. The effect of boron on crystallinity and crystallite size as well as the mechanism were presented in detailed.

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Correlation between the physical parameters of the i –nc-Si absorber layer grown by 27.12 MHz plasma with the nc-Si solar cell parameters

Cited by 39 publications

References 44 publications

Complex Dielectric Characteristics, ac-Conductivity, and Impedance Spectroscopy of B-Doped nc-SiO_X:H Thin Films

Complex Dielectric Characteristics, ac-Conductivity, and Impedance Spectroscopy of B-Doped nc-SiO_X:H Thin Films

Studies on the Impedance Characteristics, Dielectric Relaxation, and ac Conductivity in Silicon Oxycarbide (SiO_xC_y:H) Films at the Amorphous-to-Nanocrystalline Transition Zone

Boron Induced Crystallization of Silicon on Glass: an Alternate Way to Crystallize Amorphous Silicon Films for Solar Cells

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Correlation between the physical parameters of the i –nc-Si absorber layer grown by 27.12 MHz plasma with the nc-Si solar cell parameters

Cited by 39 publications

References 44 publications

Complex Dielectric Characteristics, ac-Conductivity, and Impedance Spectroscopy of B-Doped nc-SiOX:H Thin Films

Complex Dielectric Characteristics, ac-Conductivity, and Impedance Spectroscopy of B-Doped nc-SiOX:H Thin Films

Studies on the Impedance Characteristics, Dielectric Relaxation, and ac Conductivity in Silicon Oxycarbide (SiOxCy:H) Films at the Amorphous-to-Nanocrystalline Transition Zone

Boron Induced Crystallization of Silicon on Glass: an Alternate Way to Crystallize Amorphous Silicon Films for Solar Cells

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Complex Dielectric Characteristics, ac-Conductivity, and Impedance Spectroscopy of B-Doped nc-SiO_X:H Thin Films

Complex Dielectric Characteristics, ac-Conductivity, and Impedance Spectroscopy of B-Doped nc-SiO_X:H Thin Films

Studies on the Impedance Characteristics, Dielectric Relaxation, and ac Conductivity in Silicon Oxycarbide (SiO_xC_y:H) Films at the Amorphous-to-Nanocrystalline Transition Zone