Direct Nucleation of Crystalline SiGe on Substrates by Reactive Thermal CVD with Si2H6 and GeF4

1997 ◽  
Vol 467 ◽  
Author(s):  
Fumio Yoshizawa ◽  
Kunihiro Shiota ◽  
Daisuke Inoue ◽  
Jun-ichi Hanna
Keyword(s):  
Growth Rate ◽  
Gas Phase ◽  
Heterogeneous Nucleation ◽  
Homogeneous Nucleation ◽  
Film Growth ◽  
Early Stage ◽  
Gaseous Mixture ◽  
The Other ◽  
Thermal Cvd ◽  
Initial Deposition

ABSTRACTPolycrystalline SiGe (poly-SiGe) film growth by reactive thermal CVD with a gaseous mixture of Si2H6 and GeF4 was investigated on various substrates such as Al,Cr, Pt, Si, ITO, ZnO and thermally grown SiO2.In Ge-rich film growth, SEM observation in the early stage of the film growth revealed that direct nucleation of crystallites took place on the substrates. The nucleation was governed by two different mechanisms: one was a heterogeneous nucleation on the surface and the other was a homogeneous nucleation in the gas phase. In the former case, the selective nucleation was observed at temperatures lower than 400°C on metal substrates and Si, where the activation of adsorbed GeF4 on the surface played a major role for the nuclei formation, leading to the selective film growth.On the other hand, the direct nucleation did not always take place in Si-rich film growth irrespective of the substrates and depended on the growth rate. In a growth rate of 3.6nm/min, the high crystallinity of poly-Si0.95Ge0.05in a 220nm-thick film was achieved at 450°C due to the no initial deposition of amorphous tissue on SiO2 substrates.

A polycentric growth model of gallium arsenide epitaxial layers from the gas phase with simultaneous diffusion, adsorption and chemical reaction

1988 ◽  
Vol 53 (12) ◽  
pp. 2995-3013
Author(s):  
Emerich Erdös ◽  
Jindřich Leitner ◽  
Petr Voňka ◽  
Josef Stejskal ◽  
Přemysl Klíma
Keyword(s):  
Growth Rate ◽  
Gallium Arsenide ◽  
Epitaxial Growth ◽  
Gas Phase ◽  
Surface Reaction ◽  
Quantitative Description ◽  
The Other ◽  
Rate Equations ◽  
Impact Interaction ◽  
Partial Pressures

For a quantitative description of the epitaxial growth rate of gallium arsenide, two models are proposed including two rate controlling steps, namely the diffusion of components in the gas phase and the surface reaction. In the models considered, the surface reaction involves a reaction triple - or quadruple centre. In both models three mechanisms are considered which differ one from the other by different adsorption - and impact interaction of reacting particles. In every of the six cases, the pertinent rate equations were derived, and the models have been confronted with the experimentally found dependences of the growth rate on partial pressures of components in the feed. The results are discussed with regard to the plausibility of individual mechanisms and of both models, and also with respect to their applicability and the direction of further investigations.

Island Formation of SiC Film on Striated Si(001) Substrates

2008 ◽  
Vol 600-603 ◽  
pp. 227-230 ◽  
Author(s):  
Yoshimine Kato ◽  
Kazuo Sakumoto
Keyword(s):  
Growth Rate ◽  
Film Growth ◽  
Nucleation Site ◽  
The Other ◽  
Film Growth Rate ◽  
Surface Nucleation ◽  
Site Density ◽  
Other Hand ◽  
Sic Film ◽  
Nucleation Site Density

SiC growth on as-received and striated Si(001) substrates was studied. SiC films were grown by pulsed-jet chemical vapor deposition using monomethylsilane as a gas source at 780°C. Two kinds of Si surfaces were prepared. One was an as-received Si(001) surface and the other was an striated (scratched) Si(001) surface. It was found that nucleation rate of SiC is quite different between these two kinds of surfaces. The film growth rate was very low for the as-received Si(001) surface compared with the striated surface, and after 8 hours of growth hardly any film was grown and only square-shaped islands were observed. On the other hand, for the undulant substrate about 100nm thick 3C-SiC film was grown after 8 hours of deposition. This film growth rate difference appears to be due to the difference in density of nucleation sites. For the as-received Si(001) surface, nucleation site density appears to be quite small due to the atomically flat surface. On the other hand, for the undulant surface, nucleation site density was large enough for the film to grow faster.

Deposition of YSZ Thin Films by Liquid Fuel Combustion Chemical Vapor Deposition

2002 ◽  
Author(s):  
Zhigang Xu ◽  
Jag Sankar ◽  
Qiuming Wei ◽  
Jim Lua ◽  
Sergey Yamolenko ◽  
...  
Keyword(s):  
Thin Films ◽  
Growth Rate ◽  
Chemical Vapor Deposition ◽  
Substrate Temperature ◽  
Vapor Deposition ◽  
Liquid Fuel ◽  
Film Growth ◽  
Early Stage ◽  
Chemical Vapor ◽  
Nucleation Density

Thin film of YSZ electrolyte is highly desired to reduce the electrical resistance in SOFCs. YSZ thin Films have been successfully produced using liquid fuel combustion chemical vapor deposition (CCVD) technique. Nucleation of the YSZ particles were investigated based on two processing parameters, i.e., substrate temperature and total-metal-concentration in the liquid fuel. An optimum substrate temperature was found for highest the nucleation density. The nucleation density was increased with the total-metal-concentration. Microstructure evolution of the YSZ particles in the early stage in film growth was also studied. It was found that the particle growth rate was linear with processing time, and the particle orientation was varying with the time in the early stage of the film processing. To enhance the film growth rate, the effect of thermophoresis was studied. By increase the temperature gradient towards substrate, the effect of thermophoresis was enhanced and the film growth is also increased.

Use of SiCl4 as Silicon Precursor for Low-Temperature Halo-Carbon Epitaxial Growth of 4H-SiC

2010 ◽  
Vol 645-648 ◽  
pp. 111-114 ◽  
Author(s):  
Siva Prasad Kotamraju ◽  
Bharat Krishnan ◽  
Galyna Melnychuk ◽  
Yaroslav Koshka
Keyword(s):  
Growth Rate ◽  
Low Temperature ◽  
Epitaxial Growth ◽  
Gas Phase ◽  
Homogeneous Nucleation ◽  
Process Window ◽  
Carbon Precursor ◽  
Optimal Value ◽  
Similar Growth ◽  
Si Supply

Chlorinated silicon precursor SiCl4 was investigated as an alternative to SiH4 with HCl addition as a source of additional chlorine in order to suppress the homogeneous nucleation during the low-temperature epitaxial growth at 1300°C. The homogeneous nucleation in the gas phase was further reduced compared to SiH4+HCl growth. The process window for obtaining good epilayer morphology during the CH3Cl/SiCl4 growth was found to correspond to Si supply-limited mode. At lower values of C/Si ratio formation of Si-rich polycrystalline islands/droplets took place. At high C/Si ratio, formation of polycrystalline SiC was the source of morphology degradation. The process window became increasingly narrower at higher Rg, which limited the possibility of significantly increasing Rg at such low growth temperatures. Generation of triangular defects became significant at Rg above 5-6 μm/hr, even when a nearly-optimal value of C/Si ratio was used. Similar experiments were conducted using C3H8, a more traditional precursor, instead of the halo-carbon precursor CH3Cl. While a similar growth rate could be achieved for the same SiCl4 flow rate, much lower values of the C/Si ratio were required. The morphology with C3H8 was worse within the process window. The C/Si process window for the C3H8/SiCl4 growth was much narrower compared to the CH3Cl/SiCl4 growth, and the window essentially disappeared at Rg > 3 4 μm/hr.

Thin YSZ Electrolyte Film Depositions on Dense and Porous Substrates

Materials ◽  
2003 ◽  
Author(s):  
Zhigang Xu ◽  
Corydon Hilton ◽  
Bobby Watkins ◽  
Sergey Yarmolenko ◽  
Jag Sankar
Keyword(s):  
Growth Rate ◽  
Film Growth ◽  
Chemical Vapor ◽  
Deposition Process ◽  
Lanthanum Manganite ◽  
Deposition Parameters ◽  
Pore Sealing ◽  
Complex Deposition ◽  
Initial Deposition ◽  
Ysz Electrolyte

Yttria stabilized zirconia (YSZ) thin films have been processed on polished silicon and porous strontium-doped lanthanum manganite (LSM) substrates by liquid fuel combustion chemical vapor deposition from combustion of an aerosol jet. The aerosol jet consists of Y- and Zr- containing metalorganics dissolved in toluene and high-purity oxygen. The morphology and thickness of the deposited films have been analyzed with scanning electron microscope. On the polished silicon substrates, thin and uniform films have been obtained. The grain growth rate is of the first order of the deposition time. The film growth rate was greatly enhanced by utilizing higher precursor concentrations, proper substrate temperature and the effect of thermophoresis. However, when the porous substrate is being coated, a more complex deposition process takes place. The initial deposition seems to be favored on the surface protrusions. Therefore, the covered areas serve as nucleation sites and the grains start to grow, giving rise to larger particles and rougher surface than the films on polished silicon. To enhance the pore-sealing rate, some pre-treatments and post-treatment have been used. Moreover, deposition parameters towards fast pore sealing have been investigated. Thin and continuous films with the film thickness less than 3 μm have been obtained.

Effect of Si2H6 as a gas phase additive to increase growth rate of a-Si:H films and solar cells

2012 ◽  
Vol 1426 ◽  
pp. 415-420 ◽  
Author(s):  
Lala Zhu ◽  
Ujjwal K Das ◽  
Chandan Das ◽  
Steven S Hegedus
Keyword(s):  
Growth Rate ◽  
Gas Phase ◽  
Film Growth ◽  
Optical Emission ◽  
High Energy ◽  
Gas Mixtures ◽  
Layer Growth ◽  
Rf Power ◽  
Defect Parameter ◽  
Cell Efficiency

ABSTRACTWe have studied the growth rate enhancement of a-Si:H films using Si2H6 as a gas phase additive to SiH4+ H2 gas mixtures using relatively low pressure and standard 13.56 MHz RF power. With the addition of 1.7% Si2H6 in the gas mixtures (10% more Si atoms into the chamber), the a-Si:H film growth rate increased by ∼30% at 1.25 Torr and ∼60% at 2.5 Torr. The optical emission spectroscopy (OES) exhibits reduction of SiH* intensity with addition of Si2H6, which indicates the reduction of high energy electron impacts with Si containing molecules. The microstructural defect parameter (fraction of dihydride bonding in the film) appears to decrease with increase of RF power (i.e. increase of growth rate). Similar a-Si:H p-i-n cell efficiency 7-8% is achieved with and without enhanced i layer growth rate with the Si2H6additive.

Effect of Filament Material on the Decomposition of SiH4 in Hot Wire CVD of Si-Based Films

2002 ◽  
Vol 715 ◽  
Author(s):  
H. L. Duan ◽  
G. A. Zaharias ◽  
Stacey F. Bent
Keyword(s):  
Activation Energy ◽  
Growth Rate ◽  
Apparent Activation Energy ◽  
Surface Reaction ◽  
Film Growth ◽  
Activation Energies ◽  
Film Deposition ◽  
The Other ◽  
Hot Wire ◽  
Radical Production

AbstractThe choice of filament material has an effect on the decomposition of silane during the hot wire chemical vapor deposition (HW-CVD) of amorphous and microcrystalline silicon films. The Si radicals produced from W, Re, Mo and Ta filament materials have been probed by laserbased single photon ionization (SPI) as a function of hot wire temperature. The Si radical profiles are shown to demonstrate two distinct regimes: a regime below 1600°C-1800°C (depending on filament material) limited by surface reaction at the filament in which Si concentration increases monotonically; and a mass transfer limited regime above 1600°C-1800°C where Si intensity saturates. The apparent activation energy of Si radical production in the surface reaction regime from Ta (140-170 kcal/mol) is found to be close to the corresponding Si thermal desorption energy from a Ta surface, suggesting that the Si production is controlled by the desorption process from the bare metal. On the other hand, the Si activation energies from W and Re (30-60 kcal/mol) are lower than the related desorption energies, suggesting that other rate limiting reactions play a role for these materials. The apparent activation energy for the Mo surface (60-90 kcal/mol) is intermediate between the other metal values. In addition to the Si radical study, corresponding film deposition is detected in situ by multiple internal reflection infrared (MIR-IR) spectroscopy. The IR measurements have been used to estimate the growth rate of a-Si:H deposited on a Ge substrate. The results show similar activation energies for both the growth rate and the Si formation from a W filament, implying that Si radical production and subsequent film growth may be dominated by the same elementary reactions within the decomposition and film growth processes at low pressure.

Fabrication and Characterization of Polycrystalline Silicon Thin Films by Reactive Thermal CVD with Si2H6 and F2

2002 ◽  
Vol 715 ◽  
Author(s):  
J. W. Lee ◽  
K. Shimizu ◽  
J. Hanna
Keyword(s):  
Thin Films ◽  
Low Temperature ◽  
Polycrystalline Silicon ◽  
Gas Flow ◽  
Film Growth ◽  
Early Stage ◽  
High Crystallinity ◽  
Thermal Cvd ◽  
Silicon Thin Films ◽  
Transmission Electron

AbstractLow-temperature growth of polycrystalline Silicon thin films has been investigated to fabricate thin film transistors by a new thermal CVD with the reactive source gases, Si2H6 and F2, resulting in the film growth at a low-temperature less than 500°C. In order to establish the optimal condition, gas pressure, total gas flow rate of Si2H6+F2 and He as a carrier gas, and residence time, τ, were tuned. Deposition rates and film crystallinity were influenced by the gas flow rations. The growth rate was 3.2-4.2[nm/min] and film uniformity was within ±6.5% over 4cm2 area. High crystallinity films showed a sharp peak at 520[cm-1] in Raman spectra whose full width at half maximum was 6-8[cm-1]. The high crystallinity even at the early stage of film growth was confirmed by transmission electron microscopy. The conductivity and activation energy is on the order of 10-5-10-6 [S/cm] and 0.53[eV], respectively, after hydrogenation. We fabricated poly-Si bottom-gate TFT that have field effect mobility as high as 32.3cm2/Vs and on/off current ratio of 104.

A dual site growth model of gallium arsenide epitaxial layers from the gas phase

1987 ◽  
Vol 52 (5) ◽  
pp. 1131-1159
Author(s):  
Emerich Erdös ◽  
Jindřich Leitner ◽  
Petr Voňka ◽  
Josef Stejskal ◽  
Přemysl Klíma
Keyword(s):  
Growth Rate ◽  
Gallium Arsenide ◽  
Gas Phase ◽  
Quantitative Description ◽  
The Other ◽  
Rate Equations ◽  
Partial Pressures ◽  
The Individual ◽  
Rate Controlling Step ◽  
Dual Site

For a quantitative description of the epitaxial growth rate of gallium arsenide, a model is proposed including two rate controlling steps. One of these steps is the diffusion of gaseous components between the gas phase and the epitaxial layer surface, and the other step is of chemical nature, i.e. either the surface reaction or adsorption or desorption of one of the gaseous components. In the model considered, an active dual site is involved in the second rate controlling step, and twelve mechanisms are proposed for which the pertinent rate equations are derived. The individual mechanisms differ one from the other not only by the kind of the rate controlling step but also by the occupation of the dual site, viz. in the both direct and reversed direction. The proposed model is confronted with the dependences of the growth rate on partial pressures of components in the feed found by experiment. The results are discussed with regard to the possibility of individual mechanisms and of the model as a whole, and also with respect to their applicability and to the direction of further investigations.

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