Improved Passivation of a-Si:H / c-Si Interfaces Through Film Restructuring

2008 ◽  
Vol 1066 ◽  
Author(s):  
Michael Zanoni Burrows ◽  
U. K. Das ◽  
S. Bowden ◽  
S. S. Hegedus ◽  
R. L. Opila ◽  
...  
Keyword(s):  
Hydrogen Bonding ◽  
Surface Passivation ◽  
Crystalline Silicon ◽  
Silicon Surfaces ◽  
Initial Surface ◽  
Effective Lifetime ◽  
Bonding Structure ◽  
First Time ◽  
Post Deposition

ABSTRACTThe as-deposited passivation quality of amorphous silicon films on crystalline silicon surfaces is dependent on deposition conditions and resulting hydrogen bonding structure. However the initial surface passivation can be significantly improved by low temperature post-deposition anneal. For example an improvement in effective lifetime from 780 μsec as-deposited to 2080 μsec post-anneal is reported in the present work. This work probes the hydrogen bonding environment using monolayer resolution Brewster angle transmission Fourier transform infrared spectroscopy of 100 Å thick films. It is found that there is significant restructuring at the a-Si:H / c-Si interface upon annealing and a gain of mono-hydride bonding at the c-Si surface is detected. Calculations show an additional 3.56 − 4.50 × 1014 cm−2 mono-hydride bonding at c-Si surface due to annealing. The estimation of the surface hydride oscillator strength in transmission mode is reported for the first time to be 7.2 × 10−18 cm on Si (100) surface and 7.5 × 10−18 cm on Si (111).

Ultra high amorphous silicon passivation quality of crystalline silicon surface using in-situ post-deposition treatments

2014 ◽  
Vol 9 (1) ◽  
pp. 53-56 ◽  
Author(s):  
H. Meddeb ◽  
Twan Bearda ◽  
Wissem Dimassi ◽  
Yaser Abdulraheem ◽  
Hatem Ezzaouia ◽  
...  
Keyword(s):  
Amorphous Silicon ◽  
Silicon Surface ◽  
Crystalline Silicon ◽  
Post Deposition

Plasma-Texturing Processes and a-Si:H Surface Passivation on c-Si Wafers for Photovoltaic Applications

2015 ◽  
Vol 137 (5) ◽  
Author(s):  
D. Murias ◽  
M. Moreno ◽  
C. Reyes-Betanzo ◽  
A. Torres ◽  
R. Ambrosio ◽  
...  
Keyword(s):  
Surface Passivation ◽  
Crystalline Silicon ◽  
Low Cost ◽  
Process Conditions ◽  
Effective Lifetime ◽  
Heterojunction Solar Cells ◽  
Si Substrates ◽  
Photovoltaic Applications ◽  
Hydrogenated Amorphous ◽  
Better Than

In this work, we report the formation of pyramidlike structures on crystalline silicon (c-Si) substrates using plasma-texturing processes, and also, we present optimized process conditions for the deposition of hydrogenated amorphous silicon in order to passivate low cost CZ c-Si wafers. A relatively high effective lifetime of minority carriers was measured on nontextured wafers. Our results demonstrate that plasma-texturing processes can produce similar results or even better than wet-texturing processes. Finally, combined plasma texturing and passivation at low temperature is a promising approach for the fabrication of low cost heterojunction solar cells in CZ c-Si substrates.

Influence of anodic bonding on the surface passivation quality of crystalline silicon

2016 ◽  
Vol 157 ◽  
pp. 154-160 ◽  
Author(s):  
Wanghua Chen ◽  
Valérie Depauw ◽  
Farah Haddad ◽  
Jean-Luc Maurice ◽  
Pere Roca i Cabarrocas
Keyword(s):  
Surface Passivation ◽  
Crystalline Silicon ◽  
Anodic Bonding

Direct Bonding of Silicon Wafers with Simultaneous Dopant Diffusion

2001 ◽  
Vol 681 ◽  
Author(s):  
Igor V. Grekhov ◽  
Tatiana S. Agrunova ◽  
Lioudmila S. Kostina ◽  
Natalia M. Shmidt ◽  
Helmut Föll ◽  
...  
Keyword(s):  
Bonding Interface ◽  
Silicon Surfaces ◽  
Structural Quality ◽  
Water Molecules ◽  
Large Area ◽  
Type Layer ◽  
P Type ◽  
First Time ◽  
Wafer Surfaces

ABSTRACTBonding of silicon surfaces in aqueous solution of compounds containing III and IV impurities was performed for the first time. It was observed that the presence of aluminum at the bonding interface improved structural quality of the interface. This phenomenon is explained by the increase of the contact area due to Al-OH group sandwiched between the water molecules adsorbed at hydrophilic wafer surfaces at the first bonding stage. The incorporation of Al produces a p-type layer and the I/V characteristics of the resultant np+n diodes is shown not to be influenced by the presence of the bonding interface. The technique developed could be advantageous for the design of multi-layer large area semiconductor devices.

Crystalline Silicon Surface Passivation by Pecv-Deposited Hydrogenated Amorphous Silicon Oxide Films [a-SiOx:H]

2007 ◽  
Vol 989 ◽  
Author(s):  
Thomas Mueller ◽  
Wolfgang Duengen ◽  
Reinhart Job ◽  
Maximilian Scherff ◽  
Wolfgang Fahrner
Keyword(s):  
Solar Cells ◽  
Amorphous Silicon ◽  
Thermal Annealing ◽  
Surface Passivation ◽  
Crystalline Silicon ◽  
Hydrogenated Amorphous Silicon ◽  
Window Layer ◽  
Effective Lifetime ◽  
Si Solar Cells ◽  
Hydrogenated Amorphous

AbstractIn the research field of crystalline silicon (c-Si) solar cells, electronic surface passivation has been recognized as a crucial step to achieve high conversion efficiencies. The main issue of this article is to analyze the surface passivation properties of both, n-type and p-type crystalline silicon wafers by hydrogenated amorphous silicon sub oxide [a-SiOx:H] films the for use in hetero-junction (a-Si/c-Si) solar cells. A window layer is obtained with a certain fraction of oxygen in the a-SiOx:H layers.The a-SiOx:H films were deposited by decomposition of silane, carbon dioxide and hydrogen as source gases using plasma enhanced chemical vapor deposition (PECVD). Films with varying deposition parameters such as gas flow ratio (oxygen fraction) and plasma frequency (13.56, 70.0 and 110.0 MHz) are compared.To determine the passivation quality of the a-SiOx:H films, microwave-detected photo conductance decay (µ-PCD) provides a contactless measurement of the effective recombination lifetime of free carriers. The film compositions and also the changes in the microscopic structure of the amorphous network upon thermal annealing are studied using Raman spectroscopy and optical profiling techniques.The Raman spectra reveal the generation of Si-(OH)x and Si-O-Si bonds after thermal annealing in the layers, leading to a higher effective lifetime, as it reduces the defect absorption of the sub oxides.For n-type FZ material, lifetime values as high as 1650 µs are obtained, resulting in a surface recombination velocity Seff < 9.5 cm/s.

scholarly journals Understanding of Passivation Mechanism in Heterojunction c-Si Solar Cells

2008 ◽  
Vol 1066 ◽  
Author(s):  
Michio Kondo ◽  
Stefaan De Wolf ◽  
Hiroyuki Fujiwara
Keyword(s):  
Solar Cells ◽  
Epitaxial Layer ◽  
Surface Passivation ◽  
Crystalline Silicon ◽  
Amorphous Layer ◽  
Growth Direction ◽  
Boron Doped ◽  
Junction Structure ◽  
Hydrogenated Amorphous

ABSTRACTIntrinsic hydrogenated amorphous silicon (a-Si:H) films can yield in outstanding electronic surface passivation of crystalline silicon (c-Si) wafers as utilized in the HIT (heterojunction with intrinsic thin layer) solar cells. We have studied the correlation between the passivation quality and the interface nature between thin amorphous layers and an underlying c-Si substrate for understanding the passivation mechanism. We found that a thin (∼5nm) intrinsic layer is inhomogeneous along the growth direction with the presence of a hydrogen rich layer at the interface and that completely amorphous films result in better passivation quality and device performance than an epitaxial layer. Post annealing improves carrier lifetime for the amorphous layer, whereas the annealing is detrimental for the epitaxial layer. We have also found that the passivation quality of intrinsic a Si:H(i) film deteriorates severely by the presence of a boron-doped a-Si:H(p+) overlayer due to Si-H rupture in the a-Si:H(i) film. Finally, for a passivation layer in the hetero-junction structure, a-Si1−xOx will be demonstrated in comparison with a-Si:H.

Study of Surface Passivation of CZ c-Si by PECVD a-Si:H Films; A Comparison Between Quasi-Steady-State and Transient Photoconductance Decay Measurement

2013 ◽  
Vol 1536 ◽  
Author(s):  
Omid Madani Ghahfarokhi ◽  
Karsten von Maydell ◽  
Carsten Agert
Keyword(s):  
Steady State ◽  
Gas Flow ◽  
Surface Passivation ◽  
Crystalline Silicon ◽  
Chemical Vapor ◽  
Minority Carrier Lifetime ◽  
Hydrogen Gas ◽  
Quasi Steady State ◽  
Effective Lifetime ◽  
Transient Mode

ABSTRACTWe have investigated the passivation of low lifetime non-polished Czochralski (CZ) mono-crystalline silicon (c-Si) wafers by hydrogenated amorphous silicon (a-Si:H), deposited by plasma enhanced chemical vapor deposition (PECVD) technique. The dependence of the effective lifetime (τeff) on the deposition parameters including hydrogen gas flow, power and temperature has been studied. Minority carrier lifetime was measured as deposited and also after an annealing step in both quasi-steady-state (QSS) and transient mode of photoconductance decay. By comparison between τeff measured in each of the aforementioned modes, two distinguishable behaviors could be observed. Moreover, to get further insight into the surface passivation mechanism, we have modeled the recombination at a-Si:H/c-Si interface based on the amphoteric nature of dangling bonds. The results of our modeling show that the discrepancy observed between QSS and transient mode is due to the high recombination rate that exists in the bulk of defective CZ wafer and also partly related to the different thicknesses monitored in each mode. So, by comparison between the injection level dependency of τeff measured in QSS and transient modes, we introduce a valuable technique for the evaluation of c-Si bulk lifetime.

scholarly journals Sensing amorphous/crystalline silicon surface passivation by attenuated total reflection infrared spectroscopy of amorphous silicon on glass -=SUP=-*-=/SUP=-

2019 ◽  
Vol 53 (8) ◽  
pp. 1140
Author(s):  
S.N. Abolmasov ◽  
A.S. Abramov ◽  
A.V. Semenov ◽  
I.S. Shakhray ◽  
E.I. Terukov ◽  
...  
Keyword(s):  
Solar Cells ◽  
Amorphous Silicon ◽  
Silicon Surface ◽  
Surface Passivation ◽  
Crystalline Silicon ◽  
Total Reflection ◽  
Effective Lifetime ◽  
Heterojunction Solar Cells ◽  
Silicon Surface Passivation ◽  
Silicon Heterojunction Solar Cells

AbstractAttenuated total reflection Fourier transform infrared (ATR FTIR) spectroscopy and effective lifetime measurements have been used to characterize amorphous/crystalline silicon surface passivation in silicon heterojunction solar cells. The comparative studies show a strong link between microstructure factor R * and effective lifetime of amorphous silicon ( a -Si:H) passivation layers incorporating an interface buffer layer, which prevents the epitaxial growth. It is demonstrated that thin a -Si:H films deposited on glass can be used as ATR substrates in this case. The obtained results show that a -Si:H films with R * close to 0.1 are required for manufacturing of high-efficiency (>23%) silicon heterojunction solar cells.

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