Control of Materials and Interfaces in μc-Si:H-based Solar Cells Grown at High Rate

2011 ◽  
Vol 1321 ◽  
Author(s):  
Yasushi Sobajima ◽  
Chitose Sada ◽  
Akihisa Matsuda ◽  
Hiroaki Okamoto
Keyword(s):  
Growth Rate ◽  
Solar Cells ◽  
Film Growth ◽  
Defect Density ◽  
Density Measurement ◽  
High Growth ◽  
High Growth Rate ◽  
High Rate ◽  
Bulk Region ◽  
Dangling Bond

ABSTRACTGrowth process of microcrystalline silicon (μc-Si:H) using plasma-enhanced chemicalvapor- deposition method under high-rate-growth condition has been studied for the control of optoelectronic properties in the resulting materials. We have found two important things for the spatial-defect distribution in the resulting μc-Si:H through a precise dangling-bond-density measurement, e. g., (1) dangling-bond defects are uniformly distributed in the bulk region of μc- Si:H films independent of their crystallite size and (2) large number of dangling bonds are located at the surface of μc-Si:H especially when the film is deposited at high growth rate. Starting procedure of film growth has been investigated as an important process to control the dangling-bond-defect density in the bulk region of resulting μc-Si:H through the change in the electron temperature by the presence of particulates produced at the starting period of the plasma. Deposition of Si-compress thin layer on μc-Si:H grown at high rate followed by thermal annealing has been proposed as an effective method to reduce the defect density at the surface of resulting μc-Si:H. Utilizing the starting-procedure-controlling method and the compress-layerdeposition method together with several interface-controlling methods, we have demonstrated the fabrication of high conversion-efficiency (9.27%) substrate-type (n-i-p) μc-Si:H solar cells whose intrinsic μc-Si:H layer is deposited at high growth rate of 2.3 nm/sec.

High rate growth of device grade silicon thin films for solar cells

2001 ◽  
Vol 664 ◽  
Author(s):  
M. Kondo ◽  
S. Suzuki ◽  
Y. Nasuno ◽  
A. Matsuda
Keyword(s):  
Growth Rate ◽  
Solar Cells ◽  
Defect Density ◽  
Chemical Vapor ◽  
High Growth ◽  
Ion Bombardment ◽  
High Rate ◽  
Limiting Factors ◽  
Material Quality ◽  
Deuterium Dilution

ABSTRACTWe have developed a plasma enhanced chemical vapor deposition (PECVD) technique for high-rate growth of µc-Si:H at low temperatures using hydrogen diluted monosilane source gas under high-pressure depletion conditions. It was found that material qualities deteriorate, e.g. crystallinity decreases and defect density increases with increasing growth rate mainly due to ion damage from the plasma. We have found that deuterium dilution improves not only the crystallinity but also defect density as compared to hydrogen dilution and that deuterium to hydrogen ratio incorporated in the film has a good correlation with crystallinity. The advantages of the deuterium dilution are ascribed to lower ion bombardment due to slower ambipolar diffusion of deuterium ion from the plasma. Further improvement of material quality has been achieved using a triode technique where a mesh electrode inserted between cathode and anode electrodes prevents from ion bombardment. In combination with a shower head cathode, the triode technique remarkably improves the crystallinity as well as defect density at a high growth rate. As a consequence, we have succeeded to obtain much better crystallinity and uniformity at 5.8 nm/s with a defect density of 2.6×1016cm−3. We also discuss the limiting factors of growth rate and material quality for µc-Si solar cells.

Homoepitaxial growth and characterization of thick SiC layers with a reduced micropipe density

2004 ◽  
Vol 815 ◽  
Author(s):  
H. Tsuchida ◽  
I. Kamata ◽  
S. Izumi ◽  
T. Tawara ◽  
T. Jikimoto ◽  
...  
Keyword(s):  
Growth Rate ◽  
High Performance ◽  
Defect Density ◽  
Stacking Faults ◽  
High Growth ◽  
High Growth Rate ◽  
Effective Lifetime ◽  
Growth Technique ◽  
Homoepitaxial Growth

AbstractGrowth technique for thick SiC epilayers with a reduced micropipe density has been developed in a vertical hot-wall CVD reactor. Micropipe closing by growing an epilayer is possible with a nearly 100% probability for 4H-SiC substrates oriented (0001) and (000-1) off-cut towards either [11-20] or [1-100]. By applying the micropipe closing technique, a high-performance Schottky barrier diode (SBD) was demonstrated on a substrate including micropipes. Growth of low-doped and thick SiC epilayers is also possible with a good morphology at a high growth rate, and 14.4 kV blocking performance was demonstrated using a 210 μm-thick epilayer. Epitaxial growth on (000-1) substrates with low doping and a low epi-induced defect density was also demonstrated. Deep centers and impurities were investigated to determine the effective lifetime killer of the epilayers. Dislocations and stacking faults in epilayers grown on 4H-SiC substrates off-cut towards different directions were also investigated.

Development of a High Rate 4H-SiC Epitaxial Growth Technique Achieving Large-Area Uniformity

2008 ◽  
Vol 600-603 ◽  
pp. 111-114 ◽  
Author(s):  
Masahiko Ito ◽  
L. Storasta ◽  
Hidekazu Tsuchida
Keyword(s):  
Growth Rate ◽  
Epitaxial Growth ◽  
Free Exciton ◽  
High Growth ◽  
Maximum Growth ◽  
High Growth Rate ◽  
Maximum Growth Rate ◽  
High Rate ◽  
Intrinsic Defect ◽  
Large Area

A vertical hot-wall type epi-reactor that makes it possible to simultaneously achieve both a high rate of epitaxial growth and large-area uniformity at the same time has been developed. A maximum growth rate of 250 µm/h is achieved at 1650 °C. Thickness uniformity of 1.1 % and doping uniformity of 6.7 % for a 65 mm radius area are achieved while maintaining a high growth rate of 79 µm/h. We also succeeded in growing a 280 µm-thick epilayer with excellent surface morphology and long carrier lifetime of ~1 µs on average. The LTPL spectrum shows free exciton peaks as dominant, and few impurity-related or intrinsic defect related peaks are observed. The DLTS measurement for an epilayer grown at 80 µm/h shows low trap concentrations of 1.2×1012 cm-3 for Z1/2 center and 6.3×1011 cm-3 for EH6/7 center, respectively.

scholarly journals The danger of high growth combined with a large non-cash working capital base: A descriptive analysis

2002 ◽  
Vol 33 (1) ◽  
pp. 41-47
Author(s):  
W. Steyn ◽  
W. D. Hamman ◽  
E. V.D.M. Smit
Keyword(s):  
Growth Rate ◽  
Cash Flow ◽  
Descriptive Analysis ◽  
High Growth ◽  
High Growth Rate ◽  
High Rate ◽  
Working Capital ◽  
Net Profit ◽  
A Company ◽  
Operating Activities

A high growth rate may not be the ultimate measure of a successful company. This article shows that growth at too high a rate, for a company with a high non-cash working capital component, may lead to financial difficulties.While the income statement of a company is based on the accrual of income and expenses, the cash flow statement is based on the receipt and payment of cash. A company experiencing high sales growth, depending on the extent of its non-cash working capital, will find that the cash flow from operating activities before the payment of dividends will not grow as quickly as the net profit after taxation. This is because the accrual part included in the net profit after taxation is also growing at a high rate. At such a growth rate, operating activities do not generate sufficient cash to sustain the day-to-day activities of the company.

High growth rate 3C-SiC growth: from hetero-epitaxy to homo-epitaxy

MRS Advances ◽  
2016 ◽  
Vol 1 (54) ◽  
pp. 3643-3647 ◽  
Author(s):  
F. La Via ◽  
G. Litrico ◽  
R. Anzalone ◽  
A. Severino ◽  
M. Salanitri ◽  
...  
Keyword(s):  
Growth Rate ◽  
Film Thickness ◽  
Defect Density ◽  
High Growth ◽  
High Growth Rate ◽  
Sem Analysis ◽  
Final Thickness ◽  
Tem Analysis ◽  
Higher Temperature ◽  
Sic Film

Abstract 3C-SiC devices are hampered by a high crystal defect density due to the hetero-epitaxial growth of these films, which results in the presence of stacking faults (SF). In this paper high growth rate CVD processes have been used to try to reduce the SF density in 3C-SiC films. In a first step a high growth rate (30 μm/h) has been used to grow 50 μm thick 3C-SiC layer on (100) Si. Then the silicon substrate was removed via etching and a further 3C-SiC growth was performed with a higher growth rate (90 μm/h) at a higher temperature (1600 °C) to obtain a final thickness of 150 μm. The SF presence and density were evaluated by TEM analysis performed on as-grown samples and SEM analysis on KOH etched samples with various thicknesses. A decrease of SF density was observed with an increase of 3C-SiC film thickness, with the best results (500/cm) obtained for the thickest sample. The 3C-SiC film quality and orientation was evaluated by XRD are correlated with film thickness and SF density.

SiC-4H Epitaxial Layer Growth by Trichlorosilane (TCS) as Silicon Precursor at Very High Growth Rate

2008 ◽  
Vol 600-603 ◽  
pp. 123-126 ◽  
Author(s):  
Francesco La Via ◽  
Gaetano Izzo ◽  
Marco Mauceri ◽  
Giuseppe Pistone ◽  
Giuseppe Condorelli ◽  
...  
Keyword(s):  
Growth Rate ◽  
Epitaxial Layer ◽  
Structural Characterization ◽  
Defect Density ◽  
Schottky Diodes ◽  
High Growth ◽  
High Growth Rate ◽  
Layer Growth ◽  
Characterization Methods ◽  
Very High

The growth rate of 4H-SiC epi layers has been increased up to 100 µm/h with the use of trichlorosilane instead of silane as silicon precursor. The epitaxial layers grown with this process have been characterized by electrical, optical and structural characterization methods. Schottky diodes, manufactured on the epitaxial layer grown with trichlorosilane at 1600 °C, have higher yield and lower defect density in comparison to diodes realized on epilayers grown with the standard epitaxial process.

Influence of Growth Pressure and Addition of HCl Gas on Growth Rate of 4H-SiC Epitaxy

2015 ◽  
Vol 821-823 ◽  
pp. 133-136 ◽  
Author(s):  
Takanori Tanaka ◽  
Naoyuki Kawabata ◽  
Yoichiro Mitani ◽  
Masashi Sakai ◽  
Nobuyuki Tomita ◽  
...  
Keyword(s):  
Growth Rate ◽  
High Throughput ◽  
Defect Density ◽  
High Growth ◽  
High Growth Rate ◽  
Pressure Condition ◽  
High Quality ◽  
Growth Pressure ◽  
Hcl Gas

The reduction of the growth pressure was demonstrated to have the same effect as the addition of chloride-containing gas on preventing the Si nucleation and the epitaxy with high growth rate (>50 μm/h) was achieved by using the decreasing pressure condition in a horizontal CVD reactor without chloride-containing gas. The quality of a 30-μm-thick epilayer grown with 40 μm/h was also investigated. Downfall and triangle defect density in the layer was as low as 0.16 /cm2, indicating that a high quality epitaxial wafer can be easily obtained under the condition with high throughput in the sinple CVD system.

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