Real time spectroscopic ellipsometry studies of the nucleation and growth of p-type microcrystalline silicon films on amorphous silicon using B2H6, B(CH3)3 and BF3 dopant source gases

1999 ◽  
Vol 85 (8) ◽  
pp. 4141-4153 ◽  
Author(s):  
Joohyun Koh ◽  
H. Fujiwara ◽  
R. J. Koval ◽  
C. R. Wronski ◽  
R. W. Collins
Keyword(s):  
Amorphous Silicon ◽  
Real Time ◽  
Spectroscopic Ellipsometry ◽  
Nucleation And Growth ◽  
Silicon Films ◽  
Microcrystalline Silicon ◽  
P Type ◽  
Dopant Source

Nucleation of p-Type Microcrystalline Silicon on Amorphous Silicon for n-i-p Solar Cells Using B(CH3)3 And BF3 Dopant Source Gases

1998 ◽  
Vol 507 ◽  
Author(s):  
Joohyun Koh ◽  
H. Fujiwara ◽  
R. J. Koval ◽  
C. R. Wronski ◽  
R. W. Collins ◽  
...  
Keyword(s):  
Amorphous Silicon ◽  
Chemical Vapor ◽  
Rf Plasma ◽  
Structural Quality ◽  
Microcrystalline Silicon ◽  
Power Flux ◽  
Deposition Parameters ◽  
Layer Deposition ◽  
P Type ◽  
Dopant Source

ABSTRACTReal time spectroscopic ellipsometry (RTSE) has been applied to identify optimal conditions for the nucleation and growth of 120 Å microcrystalline silicon (μc-Si:H) p-layers by rf plasma-enhanced chemical vapor deposition (PECVD) at 200°C on amorphous silicon (a-Si:H) i-layers in the n-i-p solar cell configuration. Analysis of the RTSE data provide the bulk p-layer dielectric function (2.5-4.3 eV), whose amplitude and shape yield insights into the structural quality and crystallinity of the p-layer. Among the deposition parameters varied include the underlying i-layer surface treatment, the p-layer plasma power flux, and the p-layer dopant source gas and flow ratio. Here we focus on the differences between p-layer deposition using trimethyl boron, B(CH3)3, and boron trifluoride, BF3, source gases. We find significant differences attributed to the differing effects of F and CH3radicals in the plasma on silicon crystallite growth.

Nucleation and Growth of μc-Si:H n- and p-Type Layers in a-Si:H p-i-n AND n-i-p Solar Cells: Real Time Spectroellpsometry Studies

1996 ◽  
Vol 452 ◽  
Author(s):  
Joohyun Koh ◽  
H. Fujiwara ◽  
C. R. Wronskii ◽  
R. W. Collins
Keyword(s):  
Optical Properties ◽  
Solar Cells ◽  
Real Time ◽  
Size Effects ◽  
Growth Process ◽  
Nucleation And Growth ◽  
Microcrystalline Silicon ◽  
Analysis Problem ◽  
Near Surface ◽  
P Type

AbstractWe have applied real time spectroellipsometry (RTSE) to study the growth of microcrystalline silicon n- and p-layers [μc-Si:H:(P,B)] incorporated into amorphous silicon (a-Si:H) p-i-n and n-i-p solar cells, respectively. In previous research, we have applied RTSE to characterize a-Si:H solar cells having only amorphous component layers. The μc-Si:H(P,B) component layers, however, pose a more difficult RTSE analysis problem for two reasons. First, the near-surface of the underlying i-layer is modified in the μc-Si:H:(P,B) growth process, and second, the microstructural evolution near the i/(n,p) interfaces is very complicated. From RTSE spectra (1.5 < hv < 4 eV) collected every ∼4–15 s during growth, we have extracted the time evolution of the μc-Si:H:(P,B) layer microstructure, thicknesses, and optical properties along with the modifications that the near-surface i-layer properties undergo in the formation of the i/(n,p) interfaces. We suggest that the beneficial optical properties of the microcrystalline layers may be due to size effects in the crystallites that make up the films.

Nucleation Mechanism of Microcrystalline Silicon Studied by Real Time Spectroscopic Ellipsometry and Infrared Spectroscopy

2000 ◽  
Vol 609 ◽  
Author(s):  
Hiroyuki Fujiwara ◽  
Yasutake Toyoshima ◽  
Michio Kondo ◽  
Akihisa Matsuda
Keyword(s):  
Plasma Treatment ◽  
Real Time ◽  
Spectroscopic Ellipsometry ◽  
Nucleation Mechanism ◽  
Total Reflection ◽  
Attenuated Total Reflection ◽  
Reflection Spectroscopy ◽  
Microcrystalline Silicon ◽  
Strained Si ◽  
Initial Layers

ABSTRACTWe have characterized a-Si:H initial layers for μc-Si:H nucleation by real time spectroscopic ellipsometry (SE) and infrared attenuated total reflection spectroscopy (ATR) to investigate the μc-Si:H formation mechanism. By performing Ar plasma treatment of a-Si:H layers, we confirmed a presence of a 2 monolayer thick sub-surface in a-Si:H layers. In the a-Si:H sub-surface that leads to the μc-Si:H nucleation, an important peak at ∼1937 cm−1 assigned to the SiHn complex was found in the ATR spectra. From H2 plasma treatment experiments, we proposed that this SiHn complex is formed by H insertion into strained Si-Si bonds. The SiHn complex formed in the a-Si:H sub-surface showed a clear relationship with the μc-Si:H nucleation. From these results, we conclude that the μc-Si:H nucleation occurs by the formation of the chemically active and flexible SiHn complexes in the 2 monolayer thick a-Si:H sub-surface.

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.

Evolution of Crystallinity in Mixed-Phase (a+μc)-Si:H as Determined by Real Time Spectroscopic Ellipsometry

2003 ◽  
Vol 762 ◽  
Author(s):  
A. S. Ferlauto ◽  
G. M. Ferreira ◽  
R.J. Koval ◽  
J.M. Pearce ◽  
C.R. Wronski ◽  
...  
Keyword(s):  
Real Time ◽  
Spectroscopic Ellipsometry ◽  
Vapor Deposition ◽  
Volume Fraction ◽  
Cone Angle ◽  
Chemical Vapor ◽  
Mixed Phase ◽  
Thin Film Solar Cells ◽  
Nucleation Density ◽  
Microcrystalline Silicon

AbstractThe ability to characterize the phase of the intrinsic (i) layers incorporated into amorphous silicon [a-Si:H] and microcrystalline silicon [μc-Si:H] thin film solar cells is critically important for cell optimization. In our research, a new method has been developed to extract the thickness evolution of the μc-Si:H volume fraction in mixed phase amorphous + microcrystalline silicon [(a+μc)-Si:H] i-layers. This method is based on real time spectroscopic ellipsometry measurements performed during plasma-enhanced chemical vapor deposition of the films. In the analysis, the thickness at which crystallites first nucleate from the a-Si:H phase can be estimated, as well as the nucleation density and microcrystallite cone angle. The results correlate well with structural and solar cell measurements.

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