Interdigitated Back Contact Silicon Heterojunction (IBC-SHJ) Solar Cell

2007 ◽  
Vol 989 ◽  
Author(s):  
Meijun Lu ◽  
Stuart Bowden ◽  
Ujjwal Das ◽  
Michael Burrows ◽  
Robert Birkmire
Keyword(s):  
Surface Passivation ◽  
Crystalline Silicon ◽  
Spectral Response ◽  
Chemical Vapor ◽  
Front Surface ◽  
Minority Carrier Lifetime ◽  
Back Contact ◽  
Cell Structures ◽  
Current Voltage ◽  
Low Temperature Processing

AbstractInterdigitated back contact silicon heterojunction (IBC-SHJ) solar cells have been developed. This structure has interdigitated p/n amorphous silicon (a-Si:H) films deposited by plasma enhanced chemical vapor deposition (PECVD) on the backside of crystalline silicon (c-Si) wafers, with light irradiating the front surface. IBC-SHJ cells possess advantages over front junction a-Si:H/c-Si heterojunction cells due to minimized current losses in the illuminating side, and over traditional diffused back-junction cells due to low temperature processing combined with the potential of high voltages for the heterojunction. Current-voltage curves, spectral response and laser beam induced current maps have been used to characterize the IBC-SHJ cells. It was found that the IBC-SHJ cell has non-linear illumination level dependence that correlates with effective minority-carrier lifetime. As the performance of these cells is very sensitive to the quality of passivation on front surface, they are ideally suited as a diagnostic tool for detail characterization of surface passivation. Initial cell structures have achieved independently confirmed cell efficiencies of 11.8% under AM1.5 illumination. Device simulation shows an efficiency of higher than 20% can be expected after optimizing the IBC-SHJ cells.

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.

COMBINED EFFECT OF MECHANICAL GROOVING AND STAIN-ETCHED SURFACE ON OPTICAL AND ELECTRICAL PROPERTIES OF CRYSTALLINE SILICON SUBSTRATES

2014 ◽  
Vol 21 (03) ◽  
pp. 1450041 ◽  
Author(s):  
AHMED ZARROUG ◽  
LOTFI DERBALI ◽  
RACHID OUERTANI ◽  
WISSEM DIMASSI ◽  
HATEM EZZAOUIA
Keyword(s):  
Crystalline Silicon ◽  
Light Trapping ◽  
Front Surface ◽  
Minority Carrier Lifetime ◽  
Combined Effect ◽  
Machining Process ◽  
Silicon Substrates ◽  
Textured Surface ◽  
Crystalline Silicon Solar Cell ◽  
Simple Method

This paper investigates the combined effect of mechanical grooving and porous silicon (PS) on the front surface reflectance and the electronic properties of crystalline silicon substrates. Mechanical surface texturization leads to reduce the cell reflectance, enhance the light trapping and augment the carrier collection probability. PS was introduced as an efficient antireflective coating (ARC) onto the front surface of crystalline silicon solar cell. Micro-periodic V-shaped grooves were made by means of a micro-groove machining process prior to junction formation. Subsequently, wafers were subjected to an isotropic potassium hydroxide ( KOH ) etching so that the V-shape would be turned to a U-shape. We found that the successive treatment of silicon surfaces with stain-etching, grooving then alkaline etching enhances the absorption of the textured surface, and decreases the reflectance from 35% to 7% in the 300–1200 nm wavelength range. We obtained a significant increase in the overall light path that generates the building up of the light trapping inside the substrate. We found an improvement in the illuminated I–V characteristics and an increase in the minority carrier lifetime τeff. Such a simple method was adopted to effectively reinforce the overall device performance of crystalline silicon-based solar cells.

The Properties Of a-Si:H/c-Si Heterostructures Prepared By 55 kHz Pecvd For Solar Cell Application

1997 ◽  
Vol 485 ◽  
Author(s):  
B. G Budaguan ◽  
A. A. Aivazov ◽  
A. A. Sherchenkov ◽  
A. V Blrjukov ◽  
V. D. Chernomordic ◽  
...  
Keyword(s):  
Crystalline Silicon ◽  
Low Frequency ◽  
Reverse Current ◽  
Chemical Vapor ◽  
Interface State ◽  
State Density ◽  
Solar Cell Application ◽  
Current Voltage ◽  
Frequency Plasma ◽  
Device Applications

AbstractIn this work a-Si:H/c-Si heterostructures with good electronic properties of a-Si:H were prepared by 55 kHz Plasma Enhanced Chemical Vapor Deposition (PECVD). Currentvoltage and capacitance-voltage characteristics of a-Si:H/c-Si heterostructures were measuredto investigate the influence of low frequency plasma on the growing film and amorphous silicon/crystalline silicon boundary. It was established that the interface state density is low enough for device applications (<2.1010 cm−2). The current voltage measurements suggest that, when forward biased, space-charge-limited current determines the transport mechanism in a- Si:H/c-Si heterostructures, while reverse current is ascribed to the generation current in a-Si:H and c-Si depletion layers.

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.

High-temperature degradation in plasma-enhanced chemical vapor deposition Al2O3 surface passivation layers on crystalline silicon

2014 ◽  
Vol 116 (5) ◽  
pp. 054507 ◽  
Author(s):  
Saskia Kühnhold ◽  
Pierre Saint-Cast ◽  
Bishal Kafle ◽  
Marc Hofmann ◽  
Francesco Colonna ◽  
...  
Keyword(s):  
Chemical Vapor Deposition ◽  
High Temperature ◽  
Vapor Deposition ◽  
Surface Passivation ◽  
Crystalline Silicon ◽  
Chemical Vapor ◽  
Passivation Layers

scholarly journals Comparison Study of a-SiGe Solar Cells and Materials Deposited Using Different Hydrogen Dilution

2000 ◽  
Vol 609 ◽  
Author(s):  
H. Povolny ◽  
P. Agarwal ◽  
S. Han ◽  
X. Deng
Keyword(s):  
Stainless Steel ◽  
Solar Cells ◽  
Crystalline Silicon ◽  
Single Layer ◽  
Chemical Vapor ◽  
Hydrogen Dilution ◽  
Current Voltage ◽  
Ir Transmission ◽  
Cell Current ◽  
Steel Substrates

ABSTRACTA-SiGe n-i-p solar cells with i-layer deposited via plasma enhanced chemical vapor deposition (PECVD) with a germane to disilane ratio of 0.72 and hydrogen dilution R=(H2 flow)/(GeH4+Si2H6 flow) values of 1.7, 10, 30, 50, 120, 180 and 240 were deposited on stainless steel substrates. This germane to disilane ratio is what we typically use for the i-layer in the bottom cell of our standard triple-junction solar cells. Solar cell current-voltage curves (J-V) and quantum efficiency (QE) were measured for these devices. Light soaking tests were performed for these devices under 1 sun light intensity at 50° C. While device with R=30 showed the highest initial efficiency, the device with R=120 exhibit higher stabilized efficiency after 1000 hours of light soaking.Single-layer a-SiGe films (∼500 nm thick) were deposited under the same conditions as the i-layer of these devices on a variety of substrates including 7059 glass, crystalline silicon, and stainless steel for visible-IR transmission spectroscopy, FTIR, and hydrogen effusion studies. It is interesting to note 1) the H content in the film decreased with increasing R based on both the IR and H effusion measurements, and 2) while the H content changes significantly with different R, the change in Eg is relatively small. This is most likely due to a change in Ge content in the film for different R.

scholarly journals Electrical and Capacitance Diagnostic Techniques as a Support for the Development of Silicon Heterojunction Solar Cells

2014 ◽  
Vol 65 (2) ◽  
pp. 111-115 ◽  
Author(s):  
Miroslav Mikolášek ◽  
Michal Nemec ◽  
Jaroslav Kováč ◽  
Ladislav Harmatha ◽  
Lukáš Minařík
Keyword(s):  
Solar Cells ◽  
Crystalline Silicon ◽  
Diagnostic Techniques ◽  
Diagnostic Tools ◽  
Heterojunction Solar Cells ◽  
Output Performance ◽  
Cell Structures ◽  
Current Voltage ◽  
Light Management

Abstract In this paper we present the utilization of capacitance and current-voltage diagnostic techniques to analyse silicon heterojunction solar cell structures properties, particularly focused on the inspection of the amorphous emitter and amorphous silicon/crystalline silicon hetero-interface. The capacitance characterization of investigated samples have revealed the need for improvement of the a-Si:H/c-Si heterointerface quality as a main direction to obtain superior output performance of heterojunction cells. In addition, current-voltage characterization emphasized importance for enhancement of the light management in the structure. The obtained results demonstrate that electrical and capacitance diagnostic techniques can represents important diagnostic tools in the process of optimization of solar cells.

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