Comparison of Structural Properties and Solar Cell Performance of a-Si:H Films Prepared at Various Deposition Rates using 13.56 and 70 MHz PECVD Methods

2000 ◽  
Vol 609 ◽  
Author(s):  
S.J. Jones ◽  
D.L. Williamson ◽  
T. Liu ◽  
X. Deng ◽  
M. Izu
Keyword(s):  
Solar Cells ◽  
Deposition Rate ◽  
Infrared Absorption ◽  
Surface Passivation ◽  
High Growth ◽  
Density Fluctuations ◽  
Deposition Rates ◽  
Solar Cell Performance ◽  
Large Bulk ◽  
Very High Frequencies

ABSTRACTThe advantage of using very high frequencies for preparation of a-Si:H materials at high rates (above 5 Å/s) for intrinsic layers (i-layer) of solar cells has been well documented. In an effort to identify film properties which may be related to this superior device performance, a study of the structural, optical and electrical properties of films made at various deposition rates between 1 and 15 Å/s using rf frequencies of 13.56 and 70 MHz has been made. The films were characterized using a number of techniques including small-angle x-ray scattering, infrared absorption spectroscopy, and scanning electron microscopy. For the films made using the 70 MHz frequency, the amount of nanovoids with sizes of < 100Å increases systematically as the deposition rates increases beyond 5 Å/s. Accompanying the increase in void fraction in the films are increases in the hydrogen content and the amount of 2070 cm-1 mode in the infrared absorption spectra. In addition to an increase in the amount of nanovoids in the films as the deposition rate exceeds 5 Å/s, the films made using the 13.56 MHz and high deposition rates have large amounts of SAXS related to scattering features with sizes > 200 Å. This scattering is associated with large bulk density fluctuations and/or enhanced surface roughness. None of the films in the study displayed signs of having columnar-like microstructures. The nanovoids are not related to changes in the solar cells with increasing i-layer deposition rate for both fabrication processes, perhaps due to the relatively small volume fractions of less than 0.2% and/or good void-surface passivation. However, the larger-scale structures detected in the films made using the 13.56 MHz technique could cause poorer performance in cells prepared at high growth rates.

Effect of Excitation Frequency on the Performance of Amorphous Silicon Alloy Solar Cells

1998 ◽  
Vol 507 ◽  
Author(s):  
J. Yang ◽  
S. Sugiyama ◽  
S. Guha
Keyword(s):  
Solar Cells ◽  
Glow Discharge ◽  
Amorphous Silicon ◽  
Excitation Frequency ◽  
Deposition Rates ◽  
Solar Cell Performance ◽  
Single Junction ◽  
Silicon Alloy ◽  
Double Junction ◽  
Junction Structure

ABSTRACTWe have studied amorphous silicon alloy solar cells made by using a modified-very-highfrequency glow discharge at 75 MHz with a deposition rate of ∼6 Å/s. The solar cell performance is compared with those made from conventional glow discharge at 13.56 MHz with lower deposition rates. Cells made at ∼6 Å/s with 75 MHz showed comparable stabilized efficiency to those made at ∼3 Å/s with 13.56 MHz. The best performance, however, was obtained with ∼1 Å/s, including a stabilized 9.3% a-Si alloy single-junction cell employing conventional glow discharge technique. Using 75 MHz, we have achieved 11.1% and 10.0% initial active-area efficiencies for a-Si alloy and a-SiGe alloy n i p cells, respectively. An initial efficiency of 11.0% has also been obtained in a dual bandgap double-junction structure.

scholarly journals Passivation of InP solar cells using large area hexagonal-BN layers

2021 ◽  
Vol 5 (1) ◽  
Author(s):  
Vidur Raj ◽  
Dipankar Chugh ◽  
Lachlan E. Black ◽  
M. M. Shehata ◽  
Li Li ◽  
...  
Keyword(s):  
Solar Cells ◽  
Solar Cell ◽  
Surface Passivation ◽  
Defect Density ◽  
Hexagonal Boron Nitride ◽  
Cell Structure ◽  
Chemical Vapor ◽  
Large Area ◽  
Solar Cell Performance ◽  
Passivation Layers

AbstractSurface passivation is crucial for many high-performance solid-state devices, especially solar cells. It has been proposed that 2D hexagonal boron nitride (hBN) films can provide near-ideal passivation due to their wide bandgap, lack of dangling bonds, high dielectric constant, and easy transferability to a range of substrates without disturbing their bulk properties. However, so far, the passivation of hBN has been studied for small areas, mainly because of its small sizes. Here, we report the passivation characteristics of wafer-scale, few monolayers thick, hBN grown by metalorganic chemical vapor deposition. Using a recently reported ITO/i-InP/p+-InP solar cell structure, we show a significant improvement in solar cell performance utilizing a few monolayers of hBN as the passivation layer. Interface defect density (at the hBN/i-InP) calculated using C–V measurement was 2 × 1012 eV−1cm−2 and was found comparable to several previously reported passivation layers. Thus, hBN may, in the future, be a possible candidate to achieve high-quality passivation. hBN-based passivation layers can mainly be useful in cases where the growth of lattice-matched passivation layers is complicated, as in the case of thin-film vapor–liquid–solid and close-spaced vapor transport-based III–V semiconductor growth techniques.

Optical Properties of i-Layers as a Function of Growth Rate in Correlation to the Performance of a-Si:H Solar Cells

2002 ◽  
Vol 715 ◽  
Author(s):  
Keda Wang ◽  
Jessica M. Owens ◽  
Jennifer Weinberg-Wolf ◽  
Daxing Han ◽  
Lynn Gedvilas
Keyword(s):  
Growth Rate ◽  
Optical Properties ◽  
Hydrogen Bonding ◽  
Solar Cells ◽  
Solar Cell ◽  
Growth Rates ◽  
High Growth ◽  
Solar Cell Performance ◽  
Bonding Configuration ◽  
Small Absorption

Abstracta-Si:H intrinsic films and their solar cells were prepared by DC-PECVD with growth rates of 1, 3, and 10 Å/s. Raman, IR, and PL spectroscopies were used to study the i-layer properties in relation to the solar cell performance. Raman shows an identical TO mode for all the samples, which indicates the local silicon-bonding configuration does not change with the growth rate from 1 to 10 Å/s. IR results show that the hydrogen bonding configuration is monohydride (Si-H) dominated, and the hydrogen content obtained from the 630 cm-1 wagging mode is 12-14 at.%. Surprisingly, a very small absorption strength for the stretching 2000-2100 cm-1 mode was found for some samples deposited at the higher growth rates (3, 10 Å/s). For these same samples, the PL spectra exhibit a red shift. Both the IR and PL results might be related to the same microstructures formed at high growth rates. We found that although the properties of the i-layer varied as the growth rate increased from 1 to 10 Å/s, the performances of the cells were comparable (within about 4%).

Surface Passivation of p-GaTe Layered Crystals for Improved p-GaTe/n-InSe Heterojunction Solar Cells

2010 ◽  
Vol 1268 ◽  
Author(s):  
Krishna C. Mandal ◽  
Sandip Das ◽  
Ramesh Krishna ◽  
Peter G. Muzykov ◽  
Shuguo Ma ◽  
...  
Keyword(s):  
Thin Films ◽  
Solar Cells ◽  
Solar Cell ◽  
Current Density ◽  
Photoelectron Spectroscopy ◽  
Surface Passivation ◽  
Short Circuit ◽  
Solar Cell Performance ◽  
X Ray ◽  
Heterojunction Solar Cells

AbstractGaTe and GaTe:In single crystals were grown from high purity Ga (7N) and zone refined Te (>7N) precursor materials. InSe thin films were deposited by thermal evaporation onto the sulfur passivated GaTe:In substrates at various substrate temperatures from 450K-550K to fabricate p-GaTe:In/n-InSe heterojunction solar cells. Scanning electron microscopy (SEM), X-ray diffraction (XRD), electron probe microanalysis (EPMA), and X-ray photoelectron spectroscopy (XPS) were used to characterize GaTe:In crystals and InSe thin film surfaces. The current-voltage characteristics of p-GaTe:In/n-InSe solar cells were measured under dark and under illumination of 75mW/cm2. Dark J-V measurements showed that the reverse saturation current density (J0) decreased from 3.8 x 10-6 A/cm2 to 1.5 x 10-9 A/cm2 and the ideality factor was reduced from 2.04 to 1.15 as a result of surface passivation. Under illumination of 75 mW/cm2, the open-circuit voltage (Voc) increased from 0.54V to 0.68V and short-circuit current density (Jsc) increased from 7.19 mA/cm2 to 8.65 mA/cm2 for solar cells with surface passivated GaTe:In substrates, leading to an increased solar cell efficiency of 5.03%. EPMA measurements revealed that the InSe thin films deposited at 550 K on GaTe:In substrates were near stoichiometric with enhanced grain size contributing also to better solar cell performance.

He-Dilution to Increase Deposition Rate and Feedstock Utilization During the Growth of a-Si:H and a-SiGe:H Alloys

1999 ◽  
Vol 557 ◽  
Author(s):  
A. R. Middya ◽  
G. Wood ◽  
G. H. Lin ◽  
D. E. Carlson
Keyword(s):  
Solar Cells ◽  
Deposition Rate ◽  
State Of The Art ◽  
Deposition Rates ◽  
Single Junction ◽  
Hydrogen Dilution ◽  
Helium Dilution ◽  
Fabrication Time

AbstractWe report on the development of helium diluted a-Si:H and a-SiGe:H solar cells with higher deposition rates and better feedstock utilization than devices made with hydrogen dilution. Both the initial and the stabilized efficiencies of the He-diluted single-junction aSi:H and a-SiGe:H cells are similar to those of hydrogen-diluted cells with state-of-the-art intrinsic materials. The total fabrication time for tandem cells has been reduced by 17% by using helium dilution without loss in initial and stabilized efficiency.

Preparation of Triple-Junction A-Si:H NIP Based Solar Cells at Deposition Rates of 10 Å/s using a Very High Frequency Technique

1999 ◽  
Vol 557 ◽  
Author(s):  
S.J. Jones ◽  
X. Deng ◽  
T. Liu ◽  
M. Izu
Keyword(s):  
Solar Cells ◽  
Deposition Rate ◽  
Triple Junction ◽  
High Frequency ◽  
Rf Plasma ◽  
Very High Frequency ◽  
Deposition Rates ◽  
Single Junction ◽  
Layer Deposition ◽  
Very High

AbstractIn an effort to find an alternative deposition method to the standard low deposition rate 13.56 M-z PECVD technique, the feasibility of using a 70 MiHz rf plasma frequency to prepare a-Si:H based i-layer materials at high rates for nip based triple-junction solar cells has been tested. As a prelude to multi-junction cell fabrication, the deposition conditions used to make single-junction a-Si:H and a-SiGe:H cells using this Very High Frequency (VHF) method have been varied to optimize the material quality and the cell efficiencies. It was found that the efficiencies and the light stability for both a-Si:H and a-SiGe:H single-junction cells remain relatively constant as the i-layer deposition rate is varied from 1 to 10 Å/s. Also these stable efficiencies are similar to those for cells made at low deposition rates (1 Å/s) using the standard 13.56 MHz PECVD technique and the same deposition equipment. Using the knowledge obtained in the fabrication of the single-junction devices, a-Si:H/a-SiGe:H/a-SiGe:H triple-junction solar cells have been fabricated with all of the i-layers prepared using the VHF technique and deposition rates near 10 Å/s. Thin doped layers for these devices were prepared using the standard 13.56 MIHz rf frequency and deposition rates near 1 Å/s. Pre-light soaked efficiencies of greater than 10% have been obtained for these cells prepared at the high rates. In addition, after 600 hrs. of light soaking under white light conditions, the cell efficiencies degraded by only 10-13%, values similar to the degree of degradation for high efficiency triple-junction cells made by the standard 13.56 MiHz method using i-layer deposition rates near 1 Å/s. Thus, use of this VHF method in the production of large area a-Si:H based multi-junction solar modules will allow for higher i-layer deposition rates, higher module throughput and reduced module cost.

In-Situ Observation of High Deposition Rate Hydrogenated Polymorphous Silicon Cell Degradation through Variable Intensity Method Measurements

2009 ◽  
Vol 1153 ◽  
Author(s):  
Erik V Johnson ◽  
Ka-Hyun Kim ◽  
Pere Roca i Cabarrocas
Keyword(s):  
Solar Cells ◽  
Deposition Rate ◽  
High Growth ◽  
High Growth Rate ◽  
Open Circuit ◽  
High Rate ◽  
In Situ Observation ◽  
High Deposition Rate ◽  
Degradation Behaviour ◽  
Variable Intensity

AbstractThe efficiencies of hydrogenated polymorphous silicon (pm-Si:H) solar cells have been previously demonstrated to show superior stability under light-soaking. This stability arises due to the fact that the decrease they show in fill factor (FF) is partially offset by an accompanying increase in open circuit voltage (VOC). Recently, high-deposition rate (9Å/s) pm-Si:H material deposited by standard RF-PECVD at 13.56MHz has been investigated as the intrinsic layer in photovoltaic modules as it has shown excellent electronic properties. The degradation behaviour of these high-deposition rate cells, however, differs significantly from that of lower deposition rate material. In particular, no beneficial increase in Voc is observed during light soaking. We investigate the degradation dynamics of solar cells made from this high growth rate material using a Variable Illumination Method (VIM) during light soaking to quantify the changes to these high-rate cells during light-soaking and directly contrast them with those of low-rate (1.5Å/s) cells. In particular, we discuss the importance of bulk recombination effects vs interface quality changes, as well as the dynamics of changes in VOC.

Controlling Structural Evolution by VHF Power Profiling Technique for High-efficiency Microcrystalline Silicon Solar Cells at High Deposition Rate

2009 ◽  
Vol 1153 ◽  
Author(s):  
Guofu Hou ◽  
Xiaoyan Han ◽  
Changchun Wei ◽  
Xiaodan Zhang ◽  
Guijun Li ◽  
...  
Keyword(s):  
Solar Cells ◽  
Solar Cell ◽  
Deposition Rate ◽  
High Efficiency ◽  
Structural Evolution ◽  
High Rate ◽  
High Deposition Rate ◽  
Microcrystalline Silicon ◽  
Solar Cell Performance ◽  
Power Profiling

AbstractHigh rate deposition of hydrogenated microcrystalline silicon (μc-Si:H) films and solar cells were prepared by very high frequency plasma enhanced chemical vapor deposition (VHF-PECVD) process in a high power and high pressure regime. The experiment results demonstrate that in high-rate deposited μc-Si:H films, the structural evolution is much more dramatic than that in low-rate deposited μc-Si:H films. A novel VHF power profiling technique, which was designed by dynamically decreasing the VHF power step by step during the deposition of μc-Si:H intrinsic layers, has been developed to control the structural evolution along the growth direction. Another advantage of this VHF power profiling technique is the reduced ion bombardments on growth surface because of decreasing the VHF power. Using this method, a significant improvement in the solar cell performance has been achieved. A high conversion efficiency of 9.36% (Voc=542mV, Jsc=25.4mA/cm2, FF=68%) was obtained for a single junction μc-Si:H p-i-n solar cell with i-layer deposited at deposition rate over 10 �/s.

Preparation of a-Si:H and a-SiGe:H I-Layers for Nip Solar Cells at High Deposition Rates Using a Very High Frequency Technique

1998 ◽  
Vol 507 ◽  
Author(s):  
S.J. Jones ◽  
X. Deng ◽  
T. Liu ◽  
M. Izu
Keyword(s):  
Solar Cells ◽  
Deposition Rate ◽  
High Frequency ◽  
High Efficiency ◽  
High Deposition Rate ◽  
Very High Frequency ◽  
Deposition Rates ◽  
Single Junction ◽  
Layer Deposition ◽  
Very High

ABSTRACTThe 70 MHz Plasma Enhance Chemical Vapor Deposition (PECVD) technique has been tested as a high deposition rate (10 A/s) process for the fabrication of a-Si:H and a-SiGe:H alloy ilayers for high efficiency nip solar cells. As a prelude to multi-junction cell fabrication, the deposition conditions used to make single-junction a-Si:H and a-SiGe:H cells using this Very High Frequency (VHF) method have been varied to optimize the material quality and the cell efficiencies. It was found that the efficiencies and the light stability for a-Si:H single-junction cells can be made to remain relatively constant as the i-layer deposition rate is varied from 1 to 10 Å/s. Also these stable efficiencies are similar to those for cells made at low deposition rates (1 Å/s) using the standard 13.56 MHz PECVD technique. For the a-SiGe:H cells of the same i-layer thickness, use of the VHF technique leads to cells with higher currents and an ability to more easily current match triple-junction cells prepared at high deposition rates which should lead to higher multi-junction efficiencies. Thus, use of this VHF method in the production of large area a- Si:H based multi-junction solar modules will allow for higher i-layer deposition rates, higher manufacturing throughput and reduced module cost.

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