Device Quality Silicon Carbon Thin Films

2000 ◽  
Vol 609 ◽  
Author(s):  
Christian Gemmer ◽  
Markus B. Schubert
Keyword(s):  
Thin Films ◽  
Resonance Energy ◽  
Chemical Vapor ◽  
Dark Conductivity ◽  
Carbon Films ◽  
Index Of Refraction ◽  
Nanocrystalline Phase ◽  
Hydrogenated Silicon ◽  
Hydrogen Dilution ◽  
Silicon Carbon

ABSTRACTWe attain good quality hydrogenated silicon carbon films grown by plasma-enhanced chemical vapor deposition. Similar to hydrogenated silicon, we observe a characteristic edge of crystallinity at medium hydrogen dilution ratios of the feedstock gases. In the transition regime between amorphous and nanocrystalline phase, our thin films exhibit a remarkable ratio of photocarrier mobility-lifetime product to dark conductivity of 105... 106 cm3A-1 and minimum light-induced degradation. The static index of refraction increases and the resonance energy decreases for films below the onset of crystallinity which points towards a higher compactness of the protocrystalline material. Hence, alloying of hydrogenated silicon with small amounts of carbon leads to the formation of SiC:H layers that feature an optical bandgap of 2.0 eV and simultaneously maintain the superior optoelectronic properties of protocrystalline silicon.

Effect of Deposition Pressure on the Properties of Silicon Thin Films

2013 ◽  
Vol 834-836 ◽  
pp. 70-73
Author(s):  
Jing Wei Chen ◽  
Lei Zhao ◽  
Hong Wei Diao ◽  
Su Zhou ◽  
Ge Wang ◽  
...  
Keyword(s):  
Thin Films ◽  
Growth Rate ◽  
Volume Fraction ◽  
Chemical Vapor ◽  
Dark Conductivity ◽  
Deposition Pressure ◽  
Silicon Thin Film ◽  
Hydrogenated Silicon ◽  
Silicon Thin Films ◽  
Order Degree

Hydrogenated silicon thin film was prepared by plasma enhanced chemical vapor deposition (PECVD). The effects of the deposition pressure on the growth rate, the photoelectronic and microstructure properties of the thin films were investigated via transmission, photo/dark conductivity, Raman spectroscopy, and Fourier transform infrared spectroscopy (FTIR) measurements. The results indicate that the increase of the deposition pressure increases the bandgap and the growth rate, while makes the photosensitivity get worse, decreasing from more than ~103to ~102. And at the same time, the crystalline volume fraction (Xc) in the film decreases from 70% to 61%, when the deposition pressure increases from 100 Pa to 500 Pa. The order degree of the microstructure was deteriorated with pressure increasing.

Nanostructural and PL Features of nc-Si:H Thin Films Prepared by PECVD Techniques

2004 ◽  
Vol 449-452 ◽  
pp. 1017-1020
Author(s):  
J.-H. Shi ◽  
Nam Hee Cho ◽  
Seongil Im
Keyword(s):  
Thin Films ◽  
Amorphous Silicon ◽  
Chemical Vapor ◽  
Nanocrystalline Silicon ◽  
Film Structure ◽  
Nanocrystalline Phase ◽  
Dangling Bonds ◽  
Hydrogen Dilution ◽  
Key Factor ◽  
Color Sensors

Hydrogenated amorphous silicon (a-Si:H) has attracted much attention in various electronics applications such as thin films transistors, color sensors, and solar cells[1]. However, many devices made from a-S:H are observed to degrade with time, which is commonly associated with hydrogen related defects [1]. It has been observed that, by increasing the hydrogen dilution in the precursor gas used in the plasma, one can obtain hydrogenated nanocrystalline silicon (nc-Si:H), which contains crystalline grains embedded in an amorphous silicon matrix. These materials can be deposited by plasma enhanced chemical vapor deposition (PECVD) techniques. The presence of nc- Si in a-Si:H changes the optical and electronic properties of the material [2]. Nc-Si:H thin films have exhibited unique and useful characteristics. In particular, nc-Si:H thin films exhibit photoluminescence (PL) and electroluminescence (EL) behavior at room temperature [3]. The dilution of SiH4 with hydrogen has been recognized as an effective method for the transition from the amorphous to the nanocrystalline phase in the nc-Si:H thin films. The presence of hydrogen on the growing surface gives termination of dangling bonds and also an extraction of SiH3 radicals [4]. The supply balance between the hydrogen and SiH3 radicals is a key factor in determining the film structure [4]. The presence of excess hydrogen or hydrogen-bonded Si radicals (SiHn = 1, 2, 3) in the gas mixture passivates the dangling bonds on the growing surface and etches the growing surface. Etching eliminates part of the disordered structure and enhances the crystalline phase because the crystalline structure is the lowest energy configuration. In this paper, we report the study of the effects of the hydrogen species on the nanostructures and optical properties of nc-Si:H thin films prepared by PECVD techniques

Influence of Hydrogen Dilution on Electrical Properties of Amorphous Silicon Thin Films Deposited on Glass Substrates

2011 ◽  
Vol 221 ◽  
pp. 117-122
Author(s):  
Ying Ge Li ◽  
Dong Xing Du
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Electrical Properties ◽  
Amorphous Silicon ◽  
Chemical Vapor ◽  
Dark Conductivity ◽  
Thin Layers ◽  
Glass Substrates ◽  
Silicon Thin Films ◽  
Hydrogen Dilution

Thin film Amorphous Silicon materials have found wide application in photovoltaic industry. In this paper, thin layers (around 300nm) of intrinsic hydrogenated amorphous silicon (a-Si:H) are fabricated on glass (Corning Eagle2000TM) substrates by employing plasma enhanced chemical vapor deposition (PECVD) system with gas sources of silane and hydrogen. The deposited thin films are proven to be material of amorphous silicon by Raman spectroscopy measurement and their electronic transport properties are thoroughly characterized in terms of photoconductivity, dark conductivity and photo response. The effect of Hydrogen dilution on electrical properties are investigated for a-Si:H thin films deposited in the temperatures range of 150~200°C. Results indicate that a-Si:H thin films on glass substrate owns device-quality electrical properties and could be applied on fabricating thin film solar cells as the absorber layer material and on other photovoltaic or photo electronic devices.

Amorphous Silicon Selenium Alloy Film Deposited Under Hydrogen Dilution

1991 ◽  
Vol 219 ◽  
Author(s):  
Muzhi He ◽  
Guang H. Lin ◽  
J. O'M. Bockris
Keyword(s):  
Amorphous Silicon ◽  
Chemical Vapor ◽  
Selenium Concentration ◽  
Alloy Film ◽  
Dark Conductivity ◽  
Flow Rate Ratio ◽  
Selenium Atom ◽  
Alloy Films ◽  
Hydrogen Dilution ◽  
Photo Response

ABSTRACTAmorphous silicon selenium alloy films were prepared by plasma enhanced chemical vapor deposition with hydrogen dilution. The flow rate ratio of hydrogen to silane was about 8:1. Amorphous silicon selenium alloy was found to have an optical bandgap ranging from 1.7 eV to 2.0 eV depending on the selenium concentration in the films. The light to dark conductivity ratios of the alloy films are ∼ 104. The optical and electrical properties, Urbach tail energy and sub-bandgap photo response spectroscopy of the alloy film were investigated. The film quality of the alloy deposited with hydrogen dilution is greatly improved comparing to that of the alloy film deposited without hydrogen dilution. The electron spin resonance experiment shows that selenium atom is a good dangling bond terminator.

INVESTIGATION OF THE Si:H FILMS DEPOSITED NEAR THE TRANSITION REGION FOR APPLICATION IN SOLAR CELLS

2006 ◽  
Vol 20 (27) ◽  
pp. 1739-1747 ◽  
Author(s):  
QINGSONG LEI ◽  
ZHIMENG WU ◽  
XINHUA GENG ◽  
YING ZHAO ◽  
JIANPING XI
Keyword(s):  
Thin Films ◽  
Solar Cells ◽  
Transition Region ◽  
Chemical Vapor ◽  
Transition Process ◽  
Very High Frequency ◽  
Working Pressure ◽  
Hydrogenated Silicon ◽  
Silicon Thin Films ◽  
Narrow Region

Hydrogenated silicon thin films (Si:H) have been deposited by using very high-frequency plasma-enhanced chemical vapor deposition (VHF PECVD). The structural, electrical and optical properties of the films were characterized. The transition process and the effect of pressure were studied. Results suggest that a narrow region, in which the transition from microcrystalline to amorphous growth takes place, exists in the regime of silane concentration (SC). This region is influenced by the working pressure (P). At lower pressure, the transition region is shifted to higher SC. Microcrystalline silicon (μ c-Si:H ) thin films deposited near transition region was applied as i-layer to the p-i-n solar cells. An efficiency of about 5.30% was obtained.

Intrinsic and Doped m c-Si:H TFT Layers using 13.56 MHz PECVD at 250°C

2004 ◽  
Vol 808 ◽  
Author(s):  
Czang-Ho Lee ◽  
Denis Striakhilev ◽  
Arokia Nathan
Keyword(s):  
Performance Improvement ◽  
Volume Fraction ◽  
Chemical Vapor ◽  
Dark Conductivity ◽  
Rf Power ◽  
Crystalline Volume Fraction ◽  
Microcrystalline Silicon ◽  
Bias Stress ◽  
Hydrogen Dilution ◽  
Low Threshold

ABSTRACTUndoped and n+ hydrogenated microcrystalline silicon (μc-Si:H) films for thin film transistors (TFTs) were deposited at a temperature of 250°C with 99 ∼ 99.6 % hydrogen dilution of silane by standard 13.56 MHz plasma enhanced chemical vapor deposition (PECVD). High crystallinity m c-Si:H films were achieved at 99.6 % hydrogen dilution and at low rf power. An undoped 80 nm thick m c-Si:H film showed a dark conductivity of the order of 10−7 S/cm, the photosensitivity of an order of 102, and a crystalline volume fraction of 80 %. However, a 60 nm thick n+ μc-Si:H film deposited using a seed layer showed a high dark conductivity of 35 S/cm and a crystalline volume fraction of 60 %. Using n+ μc-Si:H films as drain and source contact layers in a-Si:H TFTs provides substantial performance improvement over n+ a-Si:H contacts. Finally, fully μ c-Si:H TFTs incorporating intrinsic m c-Si:H films as channel layers and n+ μc-Si:H films as contact layers have been fabricated and characterized. These TFTs exhibit a low threshold voltage and a field effect mobility of 0.85 cm2/Vs, and are far more stable under gate bias stress than a-Si:H TFTs.

Substrate temperature: A critical parameter for the growth of microcrystalline silicon-carbon alloy thin films at low power

1999 ◽  
Vol 14 (6) ◽  
pp. 2554-2559 ◽  
Author(s):  
Arup Dasgupta ◽  
S. C. Saha ◽  
Swati Ray ◽  
R. Carius
Keyword(s):  
Thin Films ◽  
Low Power ◽  
Substrate Temperature ◽  
Critical Parameter ◽  
Chemical Vapor ◽  
Microcrystalline Silicon ◽  
High Hydrogen ◽  
Deposition Parameters ◽  
Silicon Carbon ◽  
Moderate Power

P-type microcrystalline silicon-carbon alloy thin films have been prepared at low power by employing radio-frequency plasma-enhanced chemical vapor deposition (rf-PECVD) technique; judicious choice of deposition parameters is necessary. Substrate temperature has been observed to be the most critical parameter, while high hydrogen dilution is necessary but not a sufficient condition for obtaining crystallinity in silicon-carbon alloy thin films. Best microcrystallinity at moderate power density (78 mW/cm2) has been obtained at a fairly low substrate temperature (180 °C). The highest conductivity of 5.7 Scm−1 of a boron-doped microcrystalline sample could be achieved. Incorporation of carbon in these films has been confirmed from x-ray photoelectron spectroscopic (XPS) studies. Carbon is, however, incorporated only in the amorphous phase while the crystallites are of silicon only as observed from Raman spectra.

Effect of Boron Doping on Microcrystalline Germanium Carbon Thin Films

2007 ◽  
Vol 989 ◽  
Author(s):  
Yasutoshi YASHIKI ◽  
Seiichi KOUKETSU ◽  
Shinsuke MIYAJIMA ◽  
Akira YAMADA ◽  
Makoto KONAGAI
Keyword(s):  
Thin Films ◽  
Vapor Deposition ◽  
Chemical Vapor ◽  
Boron Doping ◽  
Dark Conductivity ◽  
Hot Wire ◽  
Boron Doped ◽  
Vapor Deposition Technique ◽  
Type C ◽  
P Type

AbstractEffects of boron doping on microcrystalline germanium carbon alloy (μc-Ge1-xCx:H) thin films have been investigated. We deposited boron-doped p-type μc-Ge1-xCx:H thin films by hot-wire chemical vapor deposition technique using hydrogen diluted monomethylgermane (MMG) and diborane (B2H6). A dark conductivity of 1.3 S/cm and carrier concentration of 1.7 x 1020 cm-3 were achieved with B2H6/MMG ratio of 0.1. Furthermore, the activation energy decreased from 0.37 to 0.037 eV with increasing B2H6/MMG ratio from 0 to 0.1. We also fabricated p-type μc-Ge1-xCx:H/n-type c-Si heterojunction diodes. The diodes showed rectifying characteristics. The typical ideality factor and rectifying ratio were 1.4 and 3.7 x 103 at ¡Ó 0.5 V, respectively.

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