Photoluminescence in B-doped μc-Si:H

1992 ◽  
Vol 283 ◽  
Author(s):  
S. Q. Gu ◽  
J. M. Viner ◽  
P. C. Taylor ◽  
M. J. Williams ◽  
W. A. Turner ◽  
...  
Keyword(s):  
Broad Band ◽  
Chemical Vapor ◽  
Boron Doping ◽  
Dark Conductivity ◽  
Microcrystalline Silicon ◽  
Band Tail ◽  
Pl Spectra ◽  
Photothermal Deflection Spectroscopy ◽  
Photothermal Deflection ◽  
Hydrogenated Amorphous

ABSTRACTPhotoluminescence (PL) has been investigated in hydrogenated microcrystalline silicon (μc-Si:H) samples as a function of boron doping for films prepared by remote plasma enhanced chemical vapor deposition. When the dark conductivity a is below about 10-5 S/cm, the PL spectra exhibit a shape which is close to that of the so-called band tail PL in undoped hydrogenated amorphous silicon (a-Si:H) at 77 K. When a increases, the PL intensity decreases at 77 K. For samples with a on the order of 10-3 S/cm, the PL spectra show only a narrow, low energy PL band which peaks around 0.8–0.9 eV. In these samples, the PL at higher energy is essentially not observable. This trend is similar to that which occurs in doped a-Si:H. However, for higher doping levels (σ ∼ 1 S/cm) the PL in μc-Si:H, although very weak, exhibits a broad band which contains intensity at higher energies. The absorption spectra in these samples, as measured by photothermal deflection spectroscopy (PDS), show the same relationships with the corresponding PL spectra as do the PDS spectra in doped a-Si:H.

Hydrogenated Amorphous Silicon Alloyed with Selenium

1998 ◽  
Vol 507 ◽  
Author(s):  
Shenlin Chen ◽  
P. C. Taylor ◽  
J. M. Viner
Keyword(s):  
Amorphous Silicon ◽  
Vapor Deposition ◽  
Hydrogenated Amorphous Silicon ◽  
Chemical Vapor ◽  
Band Tail ◽  
Photothermal Deflection Spectroscopy ◽  
Spin Resonance ◽  
Photo Conductivity ◽  
Photothermal Deflection ◽  
Hydrogenated Amorphous

ABSTRACTHydrogenated amorphous silicon alloyed with selenium has been made by plasma enhanced chemical vapor deposition (PECVD). The activation energy for electrical conduction is essentially unchanged for selenium concentrations < 1 at.%. The photo conductivity changes for selenium concentrations > 0.5 at. %. Photothermal deflection spectroscopy (PDS) and electron spin resonance (ESR), respectively, show that the width of the valence band tail states and the density of neutral silicon dangling bonds also change for selenium concentrations > 0.5 at. %.

Optical Properties of Microcrystalline Silicon

1989 ◽  
Vol 164 ◽  
Author(s):  
Martin Ingels ◽  
Martin Stutzmann ◽  
Stefan Zollner
Keyword(s):  
Optical Properties ◽  
Annealing Temperature ◽  
Structural Information ◽  
Optical Measurements ◽  
Microcrystalline Silicon ◽  
Grain Sizes ◽  
Photothermal Deflection Spectroscopy ◽  
Suitable Combination ◽  
Photothermal Deflection ◽  
Hydrogenated Amorphous

AbstractOptical properties of undoped, microcrystalline silicon are investigated by photothermal deflection spectroscopy, spectroscopic ellipsometry and Raman scattering. Samples are prepared by recrystallization of hydrogenated amorphous silicon in the temperature range 680 – 900°C. The increase of grain sizes with increasing annealing temperature and the disappearance of amorphous tissue lead to noticeable changes in the observed spectra. It is argued that much of the pertinent structural information of μc-Si can be obtained by a suitable combination of optical measurements alone.

Light-Induced Effects on Fluorinated Amorphous and Microcrystalline Silicon Films

1996 ◽  
Vol 420 ◽  
Author(s):  
Hong-Seok Choi ◽  
Keun-Ho Jang ◽  
Jhun-Suk Yoo ◽  
Min-Koo Han
Keyword(s):  
Band Gap ◽  
Vapor Deposition ◽  
Optical Band Gap ◽  
Silicon Film ◽  
Hydrogenated Amorphous Silicon ◽  
Chemical Vapor ◽  
Rf Plasma ◽  
Microcrystalline Silicon ◽  
Amorphous Silicon Film ◽  
Hydrogenated Amorphous

AbstractThe fluorinated amorphous and microcrystalline silicon (a,μc-Si:H;F) films have been prepared by rf plasma enhanced chemical vapor deposition (PECVD) with SiH 4 and SiF 4 gas mixtures. The stretching Si-O (1085 cm-1) and SiH2 (2100 cm-1) bands estimated from infrared (IR) spectroscope data have related to the evolution of crystallinity and the optical band gap was shifted by introducing Si-O bonds. The sub-band gap absorption coefficient in a,μc-Si:H;F films was about one order lower than that in hydrogenated amorphous silicon film (a-Si:H). The subband gap absorption in a-Si:H;F film was comparable to that in tic-Si:H;F films. The lightinduced degradation of a,μc-Si:H;F films were also suppressed.

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.

scholarly journals Photothermal Deflection Spectroscopy Study of Nanocrystalline Si (nc-Si) Thin Films Deposited on Porous Aluminum with PECVD

2012 ◽  
Vol 2012 ◽  
pp. 1-5 ◽  
Author(s):  
S. Ktifa ◽  
M. Ghrib ◽  
F. Saadallah ◽  
H. Ezzaouia ◽  
N. Yacoubi
Keyword(s):  
Optical Properties ◽  
Energy Gap ◽  
Chemical Vapor ◽  
Nanocrystalline Silicon ◽  
Porous Aluminum ◽  
Force Microscopy ◽  
Photothermal Deflection Spectroscopy ◽  
Atomic Force ◽  
Photothermal Deflection ◽  
Morphology Characterization

We have studied the optical properties of nanocrystalline silicon (nc-Si) film deposited by plasma enhancement chemical vapor deposition (PECVD) on porous aluminum structure using, respectively, the Photothermal Deflection Spectroscopy (PDS) and Photoluminescence (PL). The aim of this work is to investigate the influence of anodisation current on the optical properties of the porous aluminum silicon layers (PASL). The morphology characterization studied by atomic force microscopy (AFM) technique has shown that the grain size of (nc-Si) increases with the anodisation current. However, a band gap shift of the energy gap was observed.

DEVELOPMENT OF HIGHLY CONDUCTIVE BORON-DOPED MICROCRYSTALLINE SILICON FILMS FOR APPLICATION IN SOLAR CELLS

2006 ◽  
Vol 20 (03) ◽  
pp. 303-314 ◽  
Author(s):  
QING-SONG LEI ◽  
ZHI-MENG WU ◽  
JIAN-PING XI ◽  
XIN-HUA GENG ◽  
YING ZHAO ◽  
...  
Keyword(s):  
Solar Cells ◽  
Substrate Temperature ◽  
Chemical Vapor ◽  
Dark Conductivity ◽  
Silicon Films ◽  
Microcrystalline Silicon ◽  
Very High Frequency ◽  
Boron Doped ◽  
Deposition Processes ◽  
P Type

We have examined the deposition of highly conductive boron-doped microcrystalline silicon (μc- Si:H ) films for application in solar cells. Depositions were conducted in a very high frequency plasma enhanced chemical vapor deposition (VHF PECVD) chamber. In the deposition processes, various substrate temperatures (TS) were applied. Highly conductive p-type microcrystalline silicon films were obtained at substrate temperature lower than 210°C. The factors that affect the conductivity of the films were investigated. Results suggest that the dark conductivity, which was determined by the Hall mobility and carrier concentration, is influenced by the structure. The properties of the films are strongly dependent on the substrate temperature. With TS increasing, the dark conductivity (σd) increases initially; reach the maximum values at certain TS and then decrease. Also, we applied the boron-doped μc- Si:H as p-layers to the solar cells. An efficiency of about 8.5% for a solar cell with μc- Si:H p-layer was obtained.

Photoluminescence in Hydrogenated Amorphous Silicon with Sulfur

1996 ◽  
Vol 420 ◽  
Author(s):  
S. Chen ◽  
P. C. Taylor ◽  
S. L. Wang ◽  
J. M. Viner
Keyword(s):  
Sulfur Concentration ◽  
Absorption Coefficients ◽  
Excitation Energies ◽  
Phosphorus Doping ◽  
Pl Spectra ◽  
Sulfur Doping ◽  
Photothermal Deflection Spectroscopy ◽  
Energy Gaps ◽  
Phosphorus Doped ◽  
Hydrogenated Amorphous

AbstractPhotoluminescence (PL) has been measured at 80 K in a series of samples of sulfur doped a- Si:H using above- and below-bandgap excitation energies (2.4 and 1.38 eV). In addition, the absorption coefficients at room temperature have been obtained using photothermal deflection spectroscopy (PDS). At light sulfur doping levels (S/Si < 10-2), the Urbach slopes of the absorption coefficients on a semilog plot and the optical energy gaps, as measured by the points at which ca =104 cm-1, are independent of sulfur concentration. The slopes decrease and optical gaps increase with increasing doping level for doping levels above 10-2. At light sulfur doping levels the PL spectra excited with both above- and below-gap light are independent of sulfur concentration. For larger sulfur concentrations the shapes of the PL spectra vary. In particular, for S/Si > 10-2the peak of the PL spectrum shifts to below 0.8 eV using below-gap excitation at 1.38 eV, and the defect PL band dominates. Comparing the PL spectra of sulfur- and phosphorus-doped samples, the PL spectra change for sulfur doping above 10-2 and for phosphorus doping above 1 ppm. This trend is consistent with inefficient sulfur doping.

Evolution of Structural and Electronic Properties in Boron-doped Nanocrystalline Silicon Thin Films

2007 ◽  
Vol 989 ◽  
Author(s):  
Hyun Jung Lee ◽  
Andrei Sazonov ◽  
Arokia Nathan
Keyword(s):  
Electronic Properties ◽  
Chemical Vapor ◽  
Boron Doping ◽  
Nanocrystalline Silicon ◽  
Dark Conductivity ◽  
Crystalline Fraction ◽  
Silicon Thin Films ◽  
Boron Doped ◽  
Structural And Electronic Properties ◽  
Effective Mobility

AbstractWe report on the boron-doping dependence of the structural and electronic properties in nanocrystalline silicon (nc-Si:H) films directly deposited by plasma- enhanced chemical vapor deposition (PECVD). The crystallinity, micro-structure, and dark conductivity of the films were investigated by gradually varying the ratio of trimethylboron [B(CH3)3 or TMB] to silane (SiH4) from 0.1 to 2 %. It was found that the low level of boron doping (< 0.2 %) first compensated the nc-Si:H material which demonstrates slightly n-type properties. As the doping increased up to 0.5 %, the maximum dark conductivity (ód) of 1.11 S/cm was obtained while high crystalline fraction (Xc) of the films (over 70 %) was maintained. However, further increase in a TMB-to-SiH4 ratio reduced ód to the order of 10-7 S/cm due to a phase transition of the films from nanocrystalline to amorphous, which was indicated by Raman spectra measurements.P-channel nc-Si:H thin film transistors (TFTs) with top gate and staggered source/drain contacts were fabricated using the developed p+ nc-Si:H layer. The fabricated TFT exhibits a threshold voltage (VTp) of -26.2 V and field effective mobility of holes (μp) of 0.24 cm2/V·s.

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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