Measure of carrier lifetime in nanocrystalline silicon thin films using transmission modulated photoconductive decay

2010 ◽  
Vol 1245 ◽  
Author(s):  
Brian J. Simonds ◽  
Baojie Yan ◽  
Guozhen Yue ◽  
Donald Dunlavy ◽  
Richard K. Ahrenkiel ◽  
...  
Keyword(s):  
Thin Films ◽  
Carrier Lifetime ◽  
Volume Fraction ◽  
Nanocrystalline Silicon ◽  
Contact Method ◽  
Crystalline Volume Fraction ◽  
Effective Lifetime ◽  
Photoconductive Decay ◽  
Carrier Lifetimes ◽  
Silicon Thin Films

AbstractWe present results of extremely short carrier lifetime measurements on a series of hydrogenated nanocrystalline silicon (nc-Si:H) thin films by a novel, non-destructive, non-contact method. Transmission modulated photoconductive decay (TMPCD) is a newly developed technique which appears to have high enough sensitivity and time resolution to measure the extremely short carrier lifetimes on the order of a nanosecond. As a proof of this, we measure various nc-Si:H samples of varying crystalline volume fraction as well as a fully amorphous sample. To ascribe an effective lifetime to the materials, we use a simple model which assumes a single exponential decay. By using this model, effective lifetimes can be deconvoluted from our pump beam giving nanosecond lifetimes. Lifetimes of between 1.9 and 0.9 nanoseconds are reported and trend to decreasing lifetimes as crystalline volume fraction is increased.

The Study of Microcrystalline Silicon Thin Films Prepared by PECVD

2013 ◽  
Vol 537 ◽  
pp. 197-200
Author(s):  
Chun Ya Li ◽  
Hao Zhang ◽  
Jun Li ◽  
Xi Feng Li ◽  
Jian Hua Zhang
Keyword(s):  
Thin Films ◽  
Substrate Temperature ◽  
Process Parameters ◽  
Volume Fraction ◽  
Chemical Vapor ◽  
Silicon Films ◽  
Crystalline Volume Fraction ◽  
Microcrystalline Silicon ◽  
Reaction Pressure ◽  
Silicon Thin Films

Under different growth conditions, microcrystalline silicon thin films are deposited successfully on glass substrates by the double-frequency plasma enhanced chemical vapor deposition (PECVD). We report the systematic investigation of the effect of process parameters (hydrogen dilution, substrate temperature, forward power, reaction pressure, et al.) on the growth characteristics of microcrystalline silicon thin films. Raman scattering spectra are used to analyze the crystalline condition of the films and the experimental results. Optimizing the process parameters, the highest crystalline volume fraction of microcrystalline silicon films was achieved. It is found that the crystalline volume fraction of microcrystalline silicon films reaches 72.2% at the reaction pressure of 450 Pa, H2/SiH4 flow ratio of 800sccm/10sccm, power of 400 W and substrate temperature of 350 °C.

Study of μс-Si:H Thin Films Prepared by RF-PECVD

2014 ◽  
Vol 492 ◽  
pp. 235-238
Author(s):  
Xiao Jing Wang
Keyword(s):  
Thin Films ◽  
Grain Size ◽  
Film Thickness ◽  
Optical Band Gap ◽  
Volume Fraction ◽  
Structure And Properties ◽  
Crystalline Volume Fraction ◽  
Microcrystalline Silicon ◽  
Silicon Thin Films ◽  
Transmittance Curve

μc-Si:H thin films have been deposited on the 7059 glass substrate by RF-PECVD. Effects of film thickness on structure and properties of Si thin films were investigated by XRDRamanUV-Vis and precision multimeter. Experimental results indicated that uniform dense microcrystalline silicon thin films can be prepared by rf-PECVD, silicon thin films transferred from a-Si:H to μc-Si:H along with film thickness increased. For μc-Si:H, XRD spectrum occurred (111)(220) and (331) peak, grain size and crystalline volume fraction increased with thickness enhanced, arrived at 82%; optical band gap of μc-Si:H is 2.0~2.36eV and decreased when thickness increased, the transmittance was added firstly and then reduced with film thickness increased, the transmittance curve occurred redshift;the photosensitivity of the thin films was improved firstly and then decreased with thickness increased, which was highest at 104 quantity in the transition zone from a-Si:H to μc-Si:H.

Boron-Doped Nanocrystalline Silicon Thin Films Prepared by PECVD

2012 ◽  
Vol 503 ◽  
pp. 386-390
Author(s):  
Xiu Qin Wang ◽  
Jian Ning Ding ◽  
Ning Yi Yuan ◽  
Shu Bo Wang
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Substrate Temperature ◽  
Volume Fraction ◽  
Chemical Vapour ◽  
Nanocrystalline Silicon ◽  
Process Conditions ◽  
Rf Power ◽  
Silicon Thin Films ◽  
Boron Doped

Boron-doped nanocrystalline silicon thin films(p-nc-Si:H) were deposited on glass substrates by plasma enhanced chemical vapour deposition (PECVD) using SiH4/ H2/ B2H6. The effects of substrate temperature, rf power and diborane flow on the microstructure, the electrical properties of nanocrystalline silicon thin films have been investigated. The results show that, increasing substrate temperature, rf power and B2H6flow can improve the conductivity of P-Si thin film. However, exceeding one value, they are not advantageous to improve the conductivity due to the decrystallization of films. Hence, appropriate process conditions are crucial for the preparation of high quality p layer. crystalline volume fraction (Xc) 26.2 %, mean grain size (d) 3.5nm and conductivity 0.374S/cm, p-nc-Si:H thin film was deposited.

Giant Anisotropy of Conductivity in Hydrogenated Nanocrystalline Silicon Thin Films

1998 ◽  
Vol 536 ◽  
Author(s):  
A. B. Pevtsov ◽  
N. A. Feoktistov ◽  
V. G. Golubev
Keyword(s):  
Thin Films ◽  
Film Thickness ◽  
Percolation Theory ◽  
Nanocrystalline Silicon ◽  
Spatial Light Modulators ◽  
Light Emitting ◽  
Light Modulators ◽  
Silicon Thin Films ◽  
Longitudinal Conductivity ◽  
Transverse Conductivity

AbstractThin (<1000 Å) hydrogenated nanocrystalline silicon films are widely used in solar cells, light emitting diodes, and spatial light modulators. In this work the conductivity of doped and undoped amorphous-nanocrystalline silicon thin films is studied as a function of film thickness: a giant anisotropy of conductivity is established. The longitudinal conductivity decreases dramatically (by a factor of 109 − 1010) as the layer thickness is reduced from 1500 Å to 200 Å, while the transverse conductivity remains close to that of a doped a- Si:H. The data obtained are interpreted in terms of the percolation theory.

Research on Nanocrystalline Silicon Film Solar Cells

2011 ◽  
Vol 347-353 ◽  
pp. 870-873
Author(s):  
Chun Rong Xue
Keyword(s):  
Grain Size ◽  
Solar Cells ◽  
Band Gap ◽  
Optical Band Gap ◽  
Volume Fraction ◽  
Silicon Film ◽  
Nanocrystalline Silicon ◽  
Processing Parameters ◽  
Crystalline Volume Fraction ◽  
Hydrogen Dilution

Nanocrystalline silicon film has become the research hit of today’ s P-V solar technology. It’s optical band gap was controlled through changing the grain size and crystalline volume fraction for the quanta dimension effect. The crystalline volume fraction in nc-Si:H is modulated by varying the hydrogen concentration in the silane plasma. Also, the crystallinity of the material increases with increasing hydrogen dilution ratio, the band tail energy width of the nc-Si:H concurrently decreases. Two sets of nc-Si:H solar cells were made with different layer thicknesss, their electronic and photonic bandgap, absorption coefficient, optical band gap, nanocrystalline grain size(D), and etc have been stuied. In addition, we discussed the relationship between the stress of nc-Si thin films and H2 ratio. At last nc-Si:H solar cells have been designed and prepared successfully in the optimized processing parameters.

Nanocrystalline silicon thin films prepared by radiofrequency magnetron sputtering

2002 ◽  
Vol 403-404 ◽  
pp. 91-96 ◽  
Author(s):  
C. Gonçalves ◽  
S. Charvet ◽  
A. Zeinert ◽  
M. Clin ◽  
K. Zellama
Keyword(s):  
Thin Films ◽  
Magnetron Sputtering ◽  
Nanocrystalline Silicon ◽  
Silicon Thin Films
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