Photogeneration and Carrier Transport in Amorphous Silicon/Crystalline Silicon Devices

1997 ◽  
Vol 467 ◽  
Author(s):  
B. Jagannathan ◽  
W. A. Anderson
Keyword(s):  
Amorphous Silicon ◽  
Carrier Transport ◽  
Crystalline Silicon ◽  
Plasma Deposition ◽  
Spectral Response ◽  
Short Circuit ◽  
Short Circuit Current ◽  
Short Circuit Current Density ◽  
Open Circuit ◽  
Silicon Devices

ABSTRACTHydrogenated amorphous silicon (a-Si:H)/ crystalline silicon (c-Si) type heterodiodes in solar cell structures have been studied by rf glow discharge, dc magnetron sputtering, and a remote plasma deposition of a-Si:H onto p type c-Si. Carrier transport and photogeneration in such structures have been investigated by current-voltage-temperature, thermally stimulated capacitance (TSCAP), and spectral response experiments. Dark carrier conduction is found to be a combination of tunneling and interface recombination, but is dominated by either one depending on the deposition/sputtering conditions. The conditions investigated include energy of the plasma species, type of plasma cleaning, and substrate preparation techniques. For each of the conditions, the trap type, energy and concentration have been identified by TSCAP. Solar cells fabricated by the optimized fabrication scheme routinely yield 10.5% efficient devices having a short circuit current density (Jsc) of 30 mA/cm2, a open circuit voltage of 0.55 volts and a fill factor (FF) of 0.64, without an AR coating, over 0.3 cm2 area.

Two-Dimensional Modelling and Simulation of Crystalline Silicon n+pp+ Solar Cell

2012 ◽  
Vol 260-261 ◽  
pp. 154-162
Author(s):  
S. Tobbeche ◽  
M.N. Kateb
Keyword(s):  
Solar Cell ◽  
Open Circuit Voltage ◽  
Crystalline Silicon ◽  
Spectral Response ◽  
Short Circuit ◽  
Short Circuit Current ◽  
Short Circuit Current Density ◽  
Open Circuit ◽  
The Other ◽  
Electrical Characteristics

In this work, we present the simulation results of the technological parameters and the electrical characteristics of a crystalline silicon n+pp+ solar cell, using two-dimension (2D) software, namely TCAD Silvaco (Technology Computer Aided Design). TCAD Silvaco Athena is used to simulate various stages of the technology manufacturing, while TCAD Silvaco Atlas is used for the simulation of the electrical characteristics and the spectral response of the solar cell. The J-V characteristics and the external quantum efficiency (EQE) are simulated under AM 1.5 illumination. The conversion efficiency(η)of 16.06% is reached and the other characteristic parameters are simulated: the open circuit voltage (Voc) is of 0.63 V, the short circuit current density (Jsc) equals 30.54 mA/cm² and the form factor (FF) is of 0.83 for the n+pp+ solar cell with a silicon nitride antireflection layer (Si3N4). In order to highlight the importance of the back surface field (BSF), a comparison between two cells, one without BSF (structure n+p), the other with one BSF (structure n+pp+), was made. By creating a BSF on the rear face of the cell the short circuit current density increases from 28.55 to 30.54 mA/cm2, the open circuit voltage from 0.6 to 0.63 V and the conversion efficiency from 14.19 to 16.06%. A clear improvement of the spectral response is obtained in wavelengths ranging from 0.65 to 1.1 µm for the solar cell with BSF.

a-Si/c-Si Solar Cells: Effect of Preparation and Processing Techniques on the Photovoltaic Properties

1996 ◽  
Vol 426 ◽  
Author(s):  
B. Jagannathan ◽  
W. A. Anderson
Keyword(s):  
Solar Cells ◽  
Carrier Transport ◽  
Crystalline Silicon ◽  
Spectral Response ◽  
Short Circuit ◽  
Short Circuit Current ◽  
Short Circuit Current Density ◽  
Photovoltaic Properties ◽  
Si Solar Cells ◽  
Processing Techniques

AbstractThe photovoltaic (PV) properties of undoped amorphous silicon (a-Si)/ p-type crystalline silicon (c-Si) solar cells were found to improve by a hydrofluoric acid treatment of c-Si just prior to glow discharge deposition of a-Si. The short circuit current density (Jsc) improved from 2.7 to 23.5 mA/cm2 for an 0.1 μm thick a-Si layer. This also resulted in an improved spectral response of the solar cell in the violet region of the spectrum. The enhanced properties have been attributed to the improved carrier transport across the interface, as seen in the current-voltage-temperature relationships, and also PC-1D simulation of the devices. Solar cells of a similar type were also fabricated by dc magnetron sputtering of the a-Si layer. HF passivated cells (area ∼ 0.24 cm2) yielded about 9.5 % efficiency with Jsc of 30 mA/cm2 and a FF of 0.6, without use of an A/R coating. The variation of the PV properties of these cells was investigated as a function of a-Si thickness and c-Si doping.

Design and modeling of an SJ infrared solar cell approaching upper limit of theoretical efficiency

2018 ◽  
Vol 32 (02) ◽  
pp. 1850014 ◽  
Author(s):  
G. S. Sahoo ◽  
G. P. Mishra
Keyword(s):  
Solar Cell ◽  
Quantum Efficiency ◽  
Conversion Efficiency ◽  
Internal Quantum Efficiency ◽  
Spectral Response ◽  
Short Circuit ◽  
Cost Effective ◽  
Short Circuit Current ◽  
Short Circuit Current Density ◽  
Open Circuit

Recent trends of photovoltaics account for the conversion efficiency limit making them more cost effective. To achieve this we have to leave the golden era of silicon cell and make a path towards III–V compound semiconductor groups to take advantages like bandgap engineering by alloying these compounds. In this work we have used a low bandgap GaSb material and designed a single junction (SJ) cell with a conversion efficiency of 32.98%. SILVACO ATLAS TCAD simulator has been used to simulate the proposed model using both Ray Tracing and Transfer Matrix Method (under 1 sun and 1000 sun of AM1.5G spectrum). A detailed analyses of photogeneration rate, spectral response, potential developed, external quantum efficiency (EQE), internal quantum efficiency (IQE), short-circuit current density (J[Formula: see text]), open-circuit voltage (V[Formula: see text]), fill factor (FF) and conversion efficiency ([Formula: see text]) are discussed. The obtained results are compared with previously reported SJ solar cell reports.

scholarly journals Effect of the Phosphorus Gettering on Si Heterojunction Solar Cells

2012 ◽  
Vol 2012 ◽  
pp. 1-7 ◽  
Author(s):  
Hyomin Park ◽  
Sung Ju Tark ◽  
Chan Seok Kim ◽  
Sungeun Park ◽  
Young Do Kim ◽  
...  
Keyword(s):  
Solar Cells ◽  
Current Density ◽  
Crystalline Silicon ◽  
Short Circuit ◽  
Short Circuit Current ◽  
Short Circuit Current Density ◽  
Open Circuit ◽  
Solar Simulator ◽  
Heterojunction Solar Cells ◽  
Crystalline Silicon Solar Cells

To improve the efficiency of crystalline silicon solar cells, should be collected the excess carrier as much as possible. Therefore, minimizing the recombination both at the bulk and surface regions is important. Impurities make recombination sites and they are the major reason for recombination. Phosphorus (P) gettering was introduced to reduce metal impurities in the bulk region of Si wafers and then to improve the efficiency of Si heterojunction solar cells fabricated on the wafers. Resistivity of wafers was measured by a four-point probe method. Fill factor of solar cells was measured by a solar simulator. Saturation current and ideality factor were calculated from a dark current density-voltage graph. External quantum efficiency was analyzed to assess the effect of P gettering on the performance of solar cells. Minority bulk lifetime measured by microwave photoconductance decay increases from 368.3 to 660.8 μs. Open-circuit voltage and short-circuit current density increase from 577 to 598 mV and 27.8 to 29.8 mA/cm2, respectively. The efficiency of solar cells increases from 11.9 to 13.4%. P gettering will be feasible to improve the efficiency of Si heterojunction solar cells fabricated on P-doped Si wafers.

Preparation of Narrow-gap a-Si:H Solar Cells by VHF-PECVD Technique

2010 ◽  
Vol 1245 ◽  
Author(s):  
Do Yun Kim ◽  
Ihsanul Afdi Yunaz ◽  
Shunsuke Kasashima ◽  
Shinsuke Miyajima ◽  
Makoto Konagai
Keyword(s):  
Thin Films ◽  
Solar Cells ◽  
Solar Cell ◽  
Spectral Response ◽  
Short Circuit ◽  
Short Circuit Current ◽  
Short Circuit Current Density ◽  
Open Circuit ◽  
Hydrogen Flow ◽  
Long Wavelength

AbstractOptical, electrical and structural properties of silicon films depending on hydrogen flow rate (RH), substrate temperature (TS), and deposition pressure (PD) were investigated. By decreasing RH and increasing TS and PD, the optical band gap (Eopt) of silicon thin films drastically declined from 1.8 to 1.63 eV without a big deterioration in electrical properties. We employed all the investigated Si thin films for p-i-n structured solar cells as absorbers with i-layer thickness of 300 nm. From the measurement of solar cell performances, it was clearly observed that spectral response in long wavelength was enhanced as Eopt of absorber layers decreased. Using the solar cell whose Eopt of i-layer was 1.65 eV, the highest QE at long wavelength with the short circuit current density (Jsc) of 16.34 mA/cm2 was achieved, and open circuit voltage (Voc), fill factor (FF), and conversion efficiency (η) were 0.66 V, 0.57, and 6.13%, respectively.

Photovoltaic Characteristics of Ultra-Thin Single Crystalline Silicon Solar Cells

2016 ◽  
Vol 25 (01n02) ◽  
pp. 1640008
Author(s):  
R. Miyazawa ◽  
H. Wakabayashi ◽  
K. Tsutsui ◽  
H. Iwai ◽  
K. Kakushima
Keyword(s):  
Solar Cells ◽  
Crystalline Silicon ◽  
Spectral Response ◽  
Short Circuit ◽  
Short Circuit Current ◽  
Open Circuit ◽  
Response Measurement ◽  
Single Crystalline ◽  
Si Solar Cells ◽  
Photovoltaic Characteristics

Photovoltaic characteristics of ultra-thin single crystalline Si solar cells with thicknesses ranging from 7.6 to 3.3 nm are presented. While the short-circuit current (ISC) AM1.5 illumination has shown a linear relationship with the volume of the Si layer, a gradual increase in the open-circuit voltage (VOC) with thinner Si layer has been confirmed, implying the bandgap enlargement of the Si layer due to quantum confinement. Spectral response measurement has revealed an increased optical bandgap of 1.3 eV for 3.3-nm-thick Si solar cells, which is wider than that of 7.6-nm-thick Si ones. Although some process related issues have become clear during the fabrication of solar cells, they can be utilized as top cells for tandem configurations, exceeding the limit of the bulk Si solar cells.

Amorphous Crystalline Silicon Heterojunction with Silicon Nitride Buffer Layer

2000 ◽  
Vol 609 ◽  
Author(s):  
G. Claudio ◽  
R. De Rosa ◽  
F. Roca ◽  
D. Caputo ◽  
M. Tucci
Keyword(s):  
Silicon Nitride ◽  
Amorphous Silicon ◽  
Buffer Layer ◽  
Crystalline Silicon ◽  
Short Circuit ◽  
Wavelength Region ◽  
Visible Spectrum ◽  
Short Circuit Current ◽  
Short Circuit Current Density ◽  
Deposition Parameters

ABSTRACTIn this work we study the possibility to use amorphous silicon nitride, grown by plasma, as an alternative way to realize buffer layer in a-Si:H/c-Si heterostructure. We experimented several growing condition for silicon nitride depending on deposition parameters, obtaining samples highly transparent and with optical gap varying in the range 2.4 – 5.2 eV. We found evidence that the gap of the material is principally due to the NH3/N2 ratio. The very low absorption obtainable on this material was successfully utilized to increase the short circuit current density of the device respect to the standard cell with intrinsic amorphous silicon buffer, particularly in the low wavelength region as confirmed by quantum yield measurements. We optimized the thickness of the SiNx buffer layer respect to the photovoltaic parameters of the solar cell. A 0.5 nm thick SiNx ensures good photogeneration in blue region of the visible spectrum and does not appreciably degrade the transport mechanism of the heterojunction.

scholarly journals Improving Efficiency of Evaporated Cu2ZnSnS4Thin Film Solar Cells by a Thin Ag Intermediate Layer between Absorber and Back Contact

2015 ◽  
Vol 2015 ◽  
pp. 1-9 ◽  
Author(s):  
Hongtao Cui ◽  
Chang-Yeh Lee ◽  
Wei Li ◽  
Xiaolei Liu ◽  
Xiaoming Wen ◽  
...  
Keyword(s):  
Solar Cells ◽  
Carrier Transport ◽  
Short Circuit ◽  
Short Circuit Current ◽  
Depletion Region ◽  
Short Circuit Current Density ◽  
Open Circuit ◽  
Back Contact ◽  
Secondary Phases ◽  
P Type

A 20 nm Ag coating on Mo back contact was adopted to improve the back contact of evaporated Cu2ZnSnS4(CZTS) solar cells. The Ag layer helped reduce the thickness of MoS2which improves fill factor (FF) significantly; additionally, it reduced secondary phases ZnS and SnS2−x, which may help carrier transport; it was also involved in the doping of the absorber layer, which compensated the intrinsic p-type doping and therefore drags down the doping level. The doping involvement may enlarge the depletion region and improve lifetime of the absorber, which led to enhancing open circuit voltage (VOC), short circuit current density (JSC), and efficiency significantly. However, it degrades the crystallinity of the material slightly.

Recombination and Resistive Losses in Amorphous Silicon / Crystalline Silicon Heterojunction Solar Cells

2000 ◽  
Vol 609 ◽  
Author(s):  
Nils Jensen ◽  
Uwe Rau ◽  
Jürgen H. Werner
Keyword(s):  
Solar Cells ◽  
Carrier Transport ◽  
Fill Factor ◽  
Open Circuit Voltage ◽  
Crystalline Silicon ◽  
Internal Quantum Efficiency ◽  
Short Circuit ◽  
Short Circuit Current ◽  
Open Circuit ◽  
Absorber Material

ABSTRACTThis contribution investigates the electronic properties of a-Si:H/c-Si solar cells and explains their electrical output parameters open circuit voltage, short circuit current, and fill factor. Our device analysis is based on measurements of the internal quantum efficiency, of current/voltage and capacitance/voltage curves. We find carrier recombination within the crystalline silicon absorber material to be responsible for the limitation of the open circuit voltage. The short circuit current is restricted by collection losses in the absorber material and by absorption in the electrically inactive a-Si:H emitter. Resistive losses affecting the fill factor originate from the transport of minority carriers across the interface. The I/V curves measured at low temperatures reveal a characteristic S-shaped behavior. This effect increases with decrasing temperature and stems from the minority carrier transport, which is hindered by the band offset between a-Si:H and c-Si. We propose a new analytical model to describe this anomalous behavior.

Solar Cells on Foreign Substrates Using Poly-Si Thin Films by Metal Induced Growth

2004 ◽  
Vol 808 ◽  
Author(s):  
Chunhai Ji ◽  
Wayne A. Anderson
Keyword(s):  
Solar Cells ◽  
Ion Implantation ◽  
Spectral Response ◽  
Short Circuit ◽  
Short Circuit Current ◽  
Short Circuit Current Density ◽  
Open Circuit ◽  
Doping Density ◽  
Charge Densities ◽  
Metal Induced Growth

ABSTRACTThe poly-Si film was deposited by using the metal-induced growth (MIG) method on tungsten substrates. By making Au/n-Si Schottky photo-diodes, doping density effect was studied by using three different doping level Si sputtering targets. Increasing the Si target resistivities from 0.02Ω-cm to 50Ω-cm, open-circuit-voltage (Voc) decreased from 0.22V to 0.14V while short-circuit-current density (Jsc) increased from 1.55mA/cm2 to 2.42mA/cm2. C-V results revealed a high charge density in the device, which may be due to the oxygen thermal donor effects. Using an oxygen filter for the sputtering gas effectively reduced the charge densities and increased the Jsc value. The p/n junction solar cells were fabricated by using ion implantation at 1013∼1014cm−2 dose and 100∼200keV. The cells with wider emitter layer by double-ion implantation gave higher Jsc and Voc values. Passivation of the Si film by using hydrogenation improved the Jsc, Voc and spectral response of the solar cells.

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