Density of States of Amorphous Germanium Thin Films Deposited by the Pecvd of H2-Diluted Germane

1990 ◽  
Vol 192 ◽  
Author(s):  
C. Godet ◽  
V. Chu ◽  
B. Equer ◽  
Y. Bouizem ◽  
L. Chahed ◽  
...  
Keyword(s):  
Thin Films ◽  
Density Of States ◽  
Surface Passivation ◽  
Defect Density ◽  
Level Density ◽  
Chemical Vapor ◽  
Optical Data ◽  
Hydrogen Atoms ◽  
Bond Density ◽  
Spin Measurements

ABSTRACTThe disorder in a-Ge:H thin films produced by the plasma-enhanced chemical vapor deposition (PECVD) technique is strongly reduced when the GeH4 gas is diluted at 1% in H2 and the radiofrequency power density is increased to 0.1 W.cm−2. This improvement is attributed to a better surface passivation by the hydrogen atoms during the growth. However, the poor transport properties indicate a still high defect density. The midgap defect absorption and the Urbach energy, obtained from the photothermal deflection spectra calibrated with optical data, both decrease as a function of the film thickness. The optical defect density is calibrated with EPR spin measurements. For a-Ge:H films thicker than 2 μm, obtained at a deposition temperature Ts ranging from 150 to 250°C, the Urbach tail parameter E° is lower than 50 meV and not sensitive to Ts ; the dangling bond density is around 4.107 cm−3, which is higher by a factor of 100 than in a-Si:H. Preliminary transport measurements indicate that the Fermi level density of states is larger than 1018 cm−3.eV−1.

Intentional Reconstruction of Silicon Network on the Surface and within Sub-Surface by H and Ar

1997 ◽  
Vol 467 ◽  
Author(s):  
W. Futako ◽  
K. Fukutani ◽  
I. Shimizu
Keyword(s):  
Thin Films ◽  
Glow Discharge ◽  
Thin Layer ◽  
Defect Density ◽  
Hydrogen Atoms ◽  
Silicon Thin Films ◽  
Chemical Annealing ◽  
Rf Glow Discharge ◽  
Wide Gap ◽  
The Stability

ABSTRACTSilicon thin films were prepared by “Chemical Annealing” where the deposition of thin layer (<3 nm thick) by RF glow discharge of SiH4 and the treatment with hydrogen atoms (H) or triplet state of argon (3Ar) were repeated alternatating. Consequently, wide gap a-Si:H with the gap of 2.1 eV was made by H-treatmentat rather low substrate temperature (Ts<150 °C), while a-Si:H with the gap narrower than 1.6 eV was obtained by the treatment with 3Ar at high Ts (>300 °C), resulting from the release of excessive hydrogen. Both the wider or the narrower gap films exhibited low defect density lower than 1016 cm−3 and obvious improvements in the stability for light soaking.

Effects of Progressive SiNx Films on the Performance of Polycrystalline Silicon Solar Cells

2013 ◽  
Vol 724-725 ◽  
pp. 151-155
Author(s):  
Peng Wang ◽  
Xian Fang Gou ◽  
Wei Tao Fan ◽  
Chen Cai Sun
Keyword(s):  
Thin Films ◽  
Solar Cells ◽  
Polycrystalline Silicon ◽  
Surface Passivation ◽  
Crystalline Silicon ◽  
Chemical Vapor ◽  
Open Circuit ◽  
Electrical Performance ◽  
Silicon Solar Cells ◽  
Chemical Vapor Deposition Method

In order to improving the conversion efficiency of polycrystalline silicon solar cells, progressive SiNx thin films were deposited on the surface via Roth&Rau plasma-enhanced chemical vapor deposition method. The effects of progressive SiNx thin films, such as surface passivation, anti-reflection, and electrical performance were systematically investigated. Compared with monolayer films, progressive SiNx thin films have better anti-reflective properties in the wavelength range of 300-500 nm, resulting in improvement of the short wavelength absorption of the crystalline silicon solar cells. Moreover, the bottom of progressive SiNx thin films with high refractive index enhances the surface passivation. Thus, higher open-circuit voltage and fill factor could be obtained by this technique.

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.

scholarly journals Chemical vapor deposited polymer layer for efficient passivation of planar perovskite solar cells

2020 ◽  
Vol 8 (38) ◽  
pp. 20122-20132
Author(s):  
Mahdi Malekshahi Byranvand ◽  
Farid Behboodi-Sadabad ◽  
Abed Alrhman Eliwi ◽  
Vanessa Trouillet ◽  
Alexander Welle ◽  
...  
Keyword(s):  
Thin Films ◽  
Solar Cells ◽  
Surface Passivation ◽  
Perovskite Solar Cells ◽  
Chemical Vapor ◽  
Polymer Layer ◽  
Chemical Vapor Deposited ◽  
Passivation Layers ◽  
Substrate Temperatures

Controlling the thickness and homogeneity of thin passivation layers on polycrystalline perovskite thin films is challenging. We report CVD polymerization of poly(p-xylylene) layers at controlled substrate temperatures for efficient surface passivation of perovskite films.

Effect of Ge atoms on crystal structure and optoelectronic properties of hydrogenated Si–Ge films

2017 ◽  
Vol 31 (19-21) ◽  
pp. 1740010 ◽  
Author(s):  
Tianwei Li ◽  
Jianjun Zhang ◽  
Ying Ma ◽  
Yunwu Yu ◽  
Ying Zhao
Keyword(s):  
Silicon Germanium ◽  
Amorphous Matrix ◽  
Volume Fraction ◽  
Defect Density ◽  
Chemical Vapor ◽  
Radio Frequency Plasma ◽  
Microcrystalline Silicon ◽  
Bond Density ◽  
Hydrogen Dilution ◽  
Frequency Plasma

Optoelectronic and structural properties of hydrogenated microcrystalline silicon–germanium ([Formula: see text]c-Si[Formula: see text]Ge[Formula: see text]:H) alloys prepared by radio-frequency plasma-enhanced chemical vapor deposition (RF-PECVD) were investigated. When the Ge atoms were predominantly incorporated in amorphous matrix, the dark and photo-conductivity decreased due to the reduced crystalline volume fraction of the Si atoms (X[Formula: see text]) and the increased Ge dangling bond density. The photosensitivity decreased monotonously with Ge incorporation under higher hydrogen dilution condition, which was attributed to the increase in both crystallization of Ge and the defect density.

Mist chemical vapor deposition of aluminum oxide thin films for rear surface passivation of crystalline silicon solar cells

2014 ◽  
Vol 7 (2) ◽  
pp. 021303 ◽  
Author(s):  
Takayuki Uchida ◽  
Toshiyuki Kawaharamura ◽  
Kenji Shibayama ◽  
Takahiro Hiramatsu ◽  
Hiroyuki Orita ◽  
...  
Keyword(s):  
Thin Films ◽  
Chemical Vapor Deposition ◽  
Aluminum Oxide ◽  
Vapor Deposition ◽  
Surface Passivation ◽  
Crystalline Silicon ◽  
Rear Surface ◽  
Chemical Vapor ◽  
Silicon Solar Cells ◽  
Crystalline Silicon Solar Cells

Low Temperature Chemical Vapor Deposition Of 3C-SiC On 6H-SiC – An X-Ray Triple Crystal Diffractometry And X-Ray Topography Study

1998 ◽  
Vol 512 ◽  
Author(s):  
J. Chaudhur ◽  
K. Ignatiev ◽  
J. H. Edgar ◽  
Z. Y. Xie ◽  
Y. Gao
Keyword(s):  
Thin Films ◽  
Chemical Vapor Deposition ◽  
Low Temperature ◽  
Vapor Deposition ◽  
Defect Density ◽  
Stacking Faults ◽  
Chemical Vapor ◽  
Double Crystal ◽  
X Ray ◽  
And Inversion

Highly perfect 3C-SiC thin films, on 6H-SiC deposited by the chemical vapor deposition at low temperature with various Cl/Si, H/Si and C/Si ratios were characterized by x-ray high resolution triple crystal diffractometry and double crystal topographic methods. The films were epitaxial with a low defect density present (mostly in the range of 107/cm2). X-ray topography revealed stacking faults, low angle grain boundaries, dislocations and inversion double positioning boundaries present in the film and substrate.

Density of States in Tritiated Amorphous Silicon Measured Using CPM

2004 ◽  
Vol 836 ◽  
Author(s):  
Simone Pisana ◽  
Stefan Costea ◽  
Tome Kosteski ◽  
Nazir P. Kherani ◽  
Stefan Zukotynski ◽  
...  
Keyword(s):  
Thin Films ◽  
Amorphous Silicon ◽  
Density Of States ◽  
Defect Density ◽  
Main Type ◽  
Electronic States ◽  
Conduction Band Edge ◽  
Dangling Bond ◽  
Defect States ◽  
Silicon Thin Films

ABSTRACTThe constant photocurrent method has been used to obtain the density of occupied electronic states of tritiated amorphous silicon thin films. The analyses showed a peak of defects located 1.24 eV below the conduction band edge, suggesting that the main type of defect present in the films was a doubly occupied dangling bond. The concentration of defect states increases as a result of tritium decay by about two orders of magnitude over a period of 500 hours. The defect density in the tritiated amorphous silicon samples could be reduced by thermal annealing, after which it increased once more.

Defects in β-SiC thin films grown on α-SiC substrates

1988 ◽  
Vol 46 ◽  
pp. 568-569
Author(s):  
Karren L. More
Keyword(s):  
Thin Films ◽  
Semiconductor Device ◽  
Lattice Mismatch ◽  
Chemical Vapor ◽  
Substrate Material ◽  
Growth Interface ◽  
Si Substrates ◽  
Thermal Expansion Coefficients ◽  
Device Applications ◽  
Expansion Coefficients

Beta-SiC is an ideal candidate material for use in semiconductor device applications. Currently, monocrystalline β-SiC thin films are epitaxially grown on {100} Si substrates by chemical vapor deposition (CVD). These films, however, contain a high density of defects such as stacking faults, microtwins, and antiphase boundaries (APBs) as a result of the 20% lattice mismatch across the growth interface and an 8% difference in thermal expansion coefficients between Si and SiC. An ideal substrate material for the growth of β-SiC is α-SiC. Unfortunately, high purity, bulk α-SiC single crystals are very difficult to grow. The major source of SiC suitable for use as a substrate material is the random growth of {0001} 6H α-SiC crystals in an Acheson furnace used to make SiC grit for abrasive applications. To prepare clean, atomically smooth surfaces, the substrates are oxidized at 1473 K in flowing 02 for 1.5 h which removes ∽50 nm of the as-grown surface. The natural {0001} surface can terminate as either a Si (0001) layer or as a C (0001) layer.

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