scholarly journals Surface passivation and optical characterization of Al2O3/a-SiCx stacks on c-Si substrates

2013 ◽  
Vol 4 ◽  
pp. 726-731 ◽  
Author(s):  
Gema López ◽  
Pablo R Ortega ◽  
Cristóbal Voz ◽  
Isidro Martín ◽  
Mónica Colina ◽  
...  
Keyword(s):  
Wavelength Range ◽  
Surface Passivation ◽  
Crystalline Silicon ◽  
Surface Recombination ◽  
Chemical Vapor ◽  
Optical Characterization ◽  
Surface Recombination Velocity ◽  
Carrier Injection ◽  
Si Substrates

The aim of this work is to study the surface passivation of aluminum oxide/amorphous silicon carbide (Al2O3/a-SiCx) stacks on both p-type and n-type crystalline silicon (c-Si) substrates as well as the optical characterization of these stacks. Al2O3 films of different thicknesses were deposited by thermal atomic layer deposition (ALD) at 200 °C and were complemented with a layer of a-SiCx deposited by plasma-enhanced chemical vapor deposition (PECVD) to form anti-reflection coating (ARC) stacks with a total thickness of 75 nm. A comparative study has been carried out on polished and randomly textured wafers. We have experimentally determined the optimum thickness of the stack for photovoltaic applications by minimizing the reflection losses over a wide wavelength range (300–1200 nm) without compromising the outstanding passivation properties of the Al2O3 films. The upper limit of the surface recombination velocity (S eff,max) was evaluated at a carrier injection level corresponding to 1-sun illumination, which led to values below 10 cm/s. Reflectance values below 2% were measured on textured samples over the wavelength range of 450–1000 nm.

Photoluminescence Intensity Enhancement of GaAs by Vapor-Deposited GaS: a Rational Approach to Surface Passivation

1992 ◽  
Vol 282 ◽  
Author(s):  
Phillip P. Jenkins ◽  
Aloysius F. Hepp ◽  
Michael B. Power ◽  
Andrew R. Macinnes ◽  
Andrew R. Barrontt
Keyword(s):  
Surface Passivation ◽  
Surface Recombination ◽  
Chemical Vapor ◽  
Surface Recombination Velocity ◽  
Rational Approach ◽  
Cubic Phase ◽  
Photoluminescence Intensity ◽  
Band Bending ◽  
X Ray ◽  
Order Of Magnitude

ABSTRACTA two order-of-magnitude enhancement of photoluminescence intensity relative to untreated GaAs has been observed for GaAs surfaces coated with chemical vapor-deposited GaS. The increase in photoluminescence intensity can be viewed as an effective reduction in surface recombination velocity and/or band bending. The gallium cluster [(t-Bu)GaS]4 was used as a single-source precursor for the deposition of GaS thin films. The cubane core of the structurally-characterized precursor is retained in the deposited film producing a cubic phase. Furthermore, a near-epitaxial growth is observed for the GaS passivating layer. Films were characterized by transmission electron microscopy, X-ray powder diffraction, and X-ray photoelectron and Rutherford backscattering spectroscopies.

Interface Study Of Nanocrystalline Silicon and Crystalline Silicon Using Microwave Photoconductivity Decay

2006 ◽  
Vol 910 ◽  
Author(s):  
Mahdi Farrokh Baroughi ◽  
Siva Sivoththaman
Keyword(s):  
Crystalline Silicon ◽  
Surface Recombination ◽  
Chemical Vapor ◽  
Nanocrystalline Silicon ◽  
Interface Region ◽  
Surface Recombination Velocity ◽  
Si Substrate ◽  
Photoconductivity Decay ◽  
Recombination Velocity ◽  
Si Films

AbstractThis paper presents a measurement technique for studying of the interface between a nanocrystalline silicon (nc-Si) film and a crystalline silicon (c-Si) substrate using microwave photoconductivity decay (MWPCD). The nc-Si films were deposited using plasma enhanced chemical vapor deposition of highly hydrogen-diluted silane. The films were deposited on both sides of the high purity float-zone (FZ) Si wafers. The high resolution transmission electron microscope (HRTEM) analysis of the interface and the characterization of the effective excess carrier lifetime of the samples using MWPCD revealed the following results: (i) The crystallinity of the deposited nc-Si films is very high. The nc-Si film follows the crystal orientation of the substrate such that not a well-defined boundary between nc-Si film and the c-Si substrate is observed. (ii) A surface recombination velocity of less than 10 cm/s was measured for the interface region of the nc-Si/c-Si junctions. (iii) A small discontinuity in the band-energy diagram of the interface region was observed.

Comparison of Efficiencies of Different Surface Passivations Applied to Crystalline Silicon

2005 ◽  
Vol 108-109 ◽  
pp. 585-590 ◽  
Author(s):  
Olivier Palais ◽  
Mustapha Lemiti ◽  
Jean-Francois Lelievre ◽  
Santo Martinuzzi
Keyword(s):  
Silicon Surface ◽  
Surface Passivation ◽  
Crystalline Silicon ◽  
Surface Recombination ◽  
Surface Recombination Velocity ◽  
Phosphorus Diffusion ◽  
Type Silicon ◽  
Good Surface ◽  
Recombination Velocity ◽  
P Type

In this work the efficiencies of different surface passivation techniques are compared. This paper emphasizes on the passivation provided by SiNx:H layers that is commonly used in photovolaic industry as surface passivation and anti reflection layer. The method used to evaluate the surface recombination velocity is detailed and discussed. It is shown that light phosphorus diffusion at 850°C – 20 min provides good surface passivation of n-type silicon surface and noticeable passivation of p-type, that can be improved by SiNx:H Layer.

Improving the Conversion Efficiency and Decreasing the Thickness of the HIT Solar Cell

2009 ◽  
Vol 1210 ◽  
Author(s):  
Hirotada Inoue ◽  
Yasufumi Tsunomura ◽  
Daisuke Fujishima ◽  
Ayumu Yano ◽  
Shigeharu Taira ◽  
...  
Keyword(s):  
Solar Cells ◽  
Solar Cell ◽  
Conversion Efficiency ◽  
Surface Passivation ◽  
Crystalline Silicon ◽  
Surface Recombination ◽  
High Conversion ◽  
Surface Recombination Velocity ◽  
Substrate Thickness ◽  
High Conversion Efficiency

AbstractIn order to reduce the power-generating cost of silicon solar cells, it is necessary to achieve a high conversion efficiency using a thinner crystalline silicon (c-Si) substrate. The HIT (Heterojunction with Intrinsic Thin-layer) solar cell is an amorphous silicon (a-Si) / c-Si heterojunction solar cell that exhibits the potential to make this possible. Our recent R&D activities have achieved the world’s highest conversion efficiency of 23.0% with a practical sized (100.4 cm2) HIT solar cell, by improving the quality of the surface passivation, reducing the optical absorption loss and reducing the resistance loss. We have also developed a HIT solar cell with a thickness of only 98 mm, which has a very high conversion efficiency of 22.8%. This value is comparable to that of the conventional HIT solar cell, which has a thickness of more than 200 mm. Moreover, we have fabricated HIT solar cells using thinner c-Si substrates (96 to 58 μm), and found that the Voc increased with decreases in the substrate thickness, and reached an extremely high value of 0.745 V with a thickness of only 58 μm. This indicates that the surface recombination velocity of the HIT structure is extremely low due to the excellent passivation of the c-Si surface.

Aluminum Oxide Passivation Layer for Crystalline Silicon Solar Cells Deposited by Mist CVD in Open-Air Atmosphere

2014 ◽  
Vol 1647 ◽  
Author(s):  
Toshiyuki Kawaharamura ◽  
Takayuki Uchida ◽  
Kenji Shibayama ◽  
Shizuo Fujita ◽  
Takahiro Hiramatsu ◽  
...  
Keyword(s):  
Thin Films ◽  
Solar Cells ◽  
High Performance ◽  
Surface Passivation ◽  
Crystalline Silicon ◽  
Surface Recombination ◽  
Surface Recombination Velocity ◽  
Breakdown Field ◽  
Air Atmosphere ◽  
Si Solar Cells

ABSTRACTThe surface passivation of Si wafer by AlOx thin films grown by mist CVD in an open-air atmosphere was studied with a view to improving the effect of high-performance c-Si solar cells. In AlOx thin film grown at a temperature above 400°C by mist CVD, the OH bonding did not remain in the film and the breakdown field (EBD) was over 6 MV/cm. In Si wafers passivated by AlOx thin films grown by mist CVD at growth temperature above 400°C, the negative fixed charge density (Qf) at the interface was higher than 1012 cm-2 and the surface recombination velocity (Seff) was 44.4 cm/s. These results show that mist CVD, which is fundamentally an environmentally friendly technique, may be suitable for the fabrication of a passivation film on Si surfaces designed to improve the effect of high-performance c-Si solar cells.

Synthesis and Characterization of Highly Transparent Sol-Gel Glass for Photovoltaic Applications

2008 ◽  
Vol 1113 ◽  
Author(s):  
Mariyappan Shanmugam ◽  
Mahdi Farrokh Baroughi ◽  
XingZhong Yan ◽  
David Galipeau
Keyword(s):  
Silica Glass ◽  
Surface Passivation ◽  
Sol Gel ◽  
Surface Recombination ◽  
Cost Effective ◽  
Surface Recombination Velocity ◽  
Potential Cost ◽  
Spectral Window ◽  
Reflective Coating

ABSTRACTRoom temperature sol-gel synthesis and optical characterization of highly transparent silica glass for photovoltaic (PV) applications is presented in this paper. Tetraethyl orthosilicate (TEOS), Ethanol, Hydrochloric acid (HCl) and deionized water were used as precursors in the volumetric ratio of 4:4.3:0.1:3.2 ml. Silica glass of thickness in the range of 0.5-1 cm were obtained with an average transmittance of 93% and absorption coefficient (α) of 0.08 cm−1 in a wide wavelength window of 350-1100 nm. Application of the developed sol-gel silica glass on solar ray concentration, anti-reflective coating (ARC) and effect of surface passivation on silicon wafers were examined. Carrier lifetime of the sol-gel silica passivated silicon substrate was 16 s and the calculated surface recombination velocity of the was 2200 cm/sec. Very low value of α, high transparency in a wide spectral window and effective surface passivation on silicon suggest that sol-gel processed silica glass can be a potential cost effective candidate for different PV applications.

Characterization of a-SiCx:H Films for c-Si Surface Passivation

2002 ◽  
Vol 715 ◽  
Author(s):  
M. Vetter ◽  
I. Martín ◽  
A. Orpella ◽  
C. Voz ◽  
J. Puigdollers ◽  
...  
Keyword(s):  
Silicon Carbide ◽  
Surface Passivation ◽  
Surface Recombination ◽  
Chemical Vapor ◽  
Transmission Spectra ◽  
Infrared Transmission ◽  
Effective Surface ◽  
Doped Silicon ◽  
P Type

AbstractAmorphous intrinsic silicon carbide (a-SiCx:H(i)) films and amorphous phophorous doped silicon carbide (a-SiCx:H(n)) films deposited by plasma enhanced chemical vapor deposition (PECVD) from silane/methane mixtures provide excellent electronic passivation of p-type c-Si. Effective surface recombination velocities (Seff) lower than 23 cm s-1 have been reported for a- SiCx:H(i) films and Seff < 11 cm s-1 for a-SiCx:H(n) films. The analysis of the dependence of Seff on the injection level indicates that the good electronic passivation is due to field-effect passivation resulting from a high fixed charge (Qf) created in the a-SiCx:H film. In this work the absorption of SiH bonds in infrared transmission spectra of a-SiCx:H films is quantitatively analysed resulting in about 30% smaller amount of SiH bonds in phosphorous doped films compared to intrinsic films. Furthermore, a strong reciprocal correlation of the hydrogen content in the films and the Qf created at the a-SiCx:H/c-Si interface is observed.

Investigation of Surface Passivation in InAs/GaSb Strained-Layer-Superlattices Using Picosecond Excitation Correlation Measurement and Variable-Area Diode Array Surface Recombination Velocity Measurement

2005 ◽  
Vol 891 ◽  
Author(s):  
Zhimei Zhu ◽  
Elena Plis ◽  
Abdenour Amtout ◽  
Pallab Bhattacharya ◽  
Sanjay Krishna
Keyword(s):  
Infrared Detectors ◽  
Surface Passivation ◽  
Surface Recombination ◽  
Surface States ◽  
Depletion Region ◽  
Surface Recombination Velocity ◽  
Diode Array ◽  
Ammonium Sulfide ◽  
Picosecond Excitation ◽  
Recombination Velocity

ABSTRACTThe effect of ammonium sulfide passivation on InAs/GaSb superlattice infrared detectors was investigated using two complementary techniques, namely, picosecond excitation correlation (PEC) measurement and variable-area diode array (VADA) surface recombination velocity (SRV) measurement. PEC measurements were conducted on etched InAs/GaSb superlattice mesas, which were passivated in aqueous ammonium sulfide solutions of various strengths for several durations. The PEC signal's decay time constant (DTC) is proportional to carrier lifetimes. At 77 K the PEC signal's DTC of the as-grown InAs/GaSb superlattice sample was 2.0 ns, while that of the unpassivated etched sample was reduced to 1.2 ns by the surface states at the mesa sidewalls. The most effective ammonium sulfide passivation process increased the PEC signal's DTC to 10.4 ns. However it is difficult to isolate surface recombination from other processes that contribute to the lifetime using the PEC data, therefore a VADA SRV measurement was undertaken to determine the effect of passivation on surface recombination. The obtained SRV in the depletion region of the InAs/GaSb superlattice and GaSb junction was 1.1×106 cm/s for the unpassivated sample and 4.6×105 cm/s for the passivated sample. At 77 K the highest R0A value measured in our passivated devices was 2540 W cm2 versus 0.22 W cm2 for the unpassivated diodes. The results of the lifetime, the SRV and the R0A measurements indicate that ammonium sulfide passivation will improve the performance of InAs/GaSb superlattice infrared detectors.

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