MBE Growth of GaN Films in Presence of Surfactants: The Effect of Mg and Si

1999 ◽  
Vol 595 ◽  
Author(s):  
Guido Mula ◽  
Bruno Daudin ◽  
Christoph Adelmann ◽  
Philippe Peyla
Keyword(s):  
Growth Rate ◽  
Theoretical Model ◽  
Diffusion Barriers ◽  
Surface Kinetics ◽  
Growth Behaviour ◽  
Mbe Growth ◽  
Foreign Species

AbstractWe present here a description and an analysis of the modifications in the growth behaviour of GaN induced by the presence of foreign species. The particular cases of Mg and Si are analysed. Profound changes, both in microscopic and macroscopic scales, occur in presence of Mg, even for fluxes of about 1/1000th of the Ga flux. The growth rate can be increased by almost 50%, depending of the III/V ratio and on the amount of Mg. A theoretical model is proposed to describe the observed effect. It is found that Mg induces changes in the Ga and N diffusion barriers and acts as a surfactant. The effect is stronger on the a-GaN than on the α-GaN, where N is more tightly bonded. The effect of Si is by far less pronounced, probably because it is more easily incorporated than Mg, and its effect on the surface kinetics is then strongly reduced.

scholarly journals MBE Growth Of GaN Films In Presence Of Surfactants: The Effect Of Mg And Si

2000 ◽  
Vol 5 (S1) ◽  
pp. 202-208 ◽  
Author(s):  
Guido Mula ◽  
Bruno Daudin ◽  
Christoph Adelmann ◽  
Philippe Peyla
Keyword(s):  
Growth Rate ◽  
Theoretical Model ◽  
Diffusion Barriers ◽  
Surface Kinetics ◽  
Growth Behaviour ◽  
Mbe Growth ◽  
Foreign Species

We present here a description and an analysis of the modifications in the growth behaviour of GaN induced by the presence of foreign species. The particular cases of Mg and Si are analysed. Profound changes, both in microscopic and macroscopic scales, occur in presence of Mg, even for fluxes of about 1/1000th of the Ga flux. The growth rate can be increased by almost 50%, depending of the III/V ratio and on the amount of Mg. A theoretical model is proposed to describe the observed effect. It is found that Mg induces changes in the Ga and N diffusion barriers and acts as a surfactant. The effect is stronger on the α-GaN than on the β-GaN, where N is more tightly bonded. The effect of Si is by far less pronounced, probably because it is more easily incorporated than Mg, and its effect on the surface kinetics is then strongly reduced.

Effect of Constraint Induced by Specimen Geometries on Crack Growth Behavior Under Creep-Fatigue Interaction

2018 ◽  
Author(s):  
Lei Zhao ◽  
Lianyong Xu
Keyword(s):  
Growth Rate ◽  
Crack Growth Rate ◽  
Crack Growth ◽  
Growth Rates ◽  
Crack Tip ◽  
Crack Growth Behavior ◽  
Growth Behaviour ◽  
Crack Growth Behaviour ◽  
Creep Fatigue ◽  
Crack Growth Rates

Creep-fatigue interaction would accelerate the crack growth behaviour and change the crack growth mode, which is different from that presenting in pure creep or fatigue regimes. In addition, the constraint ahead of crack tip affects the relationship between crack growth rate and fracture mechanics and thus affects the accuracy of the life prediction for high-temperature components containing defects. In this study, to reveal the role of constraint caused by various specimen geometries in the creep-fatigue regime, five different types of cracked specimens (including C-ring in tension CST, compact tension CT, single notch tension SENT, single notch bend SENB, middle tension MT) were employed. The crack growth and damage evolution behaviours were simulated using finite element method based on a non-linear creep-fatigue interaction damage model considering creep damage, fatigue damage and interaction damage. The expression of (Ct)avg for different specimen geometries were given. Then, the variation of crack growth behaviour with various specimen geometries under creep-fatigue conditions were analysed. CT and CST showed the highest crack growth rates, which were ten times as the lowest crack growth rates in MT. This revealed that distinctions in specimen geometry influenced the in-plane constraint level ahead of crack tip. Furthermore, a load-independent constraint parameter Q* was introduced to correlate the crack growth rate. The sequence of crack growth rate at a given value of (Ct)avg was same to the reduction of Q*, which shown a linear relation in log-log curve.

A RHEED Study of MBE Growth of ZnSe on GaAs (111) A-(2 × 2)

2003 ◽  
Vol 10 (04) ◽  
pp. 669-675
Author(s):  
F. S. Gard ◽  
J. D. Riley ◽  
R. Leckey ◽  
B. F. Usher
Keyword(s):  
Growth Rate ◽  
Electron Diffraction ◽  
Substrate Temperature ◽  
Three Dimensional ◽  
High Energy ◽  
Growth Mode ◽  
Two Dimensional ◽  
High Energy Electron ◽  
Mbe Growth ◽  
Atomic Flux

ZnSe epilayers have been grown under various Se/Zn atomic flux ratios in the range of 0.22–2.45 at a substrate temperature of 350°C on Zn pre-exposed GaAs (111) A surfaces. Real time reflection high energy electron diffraction (RHEED) observations have shown a transition from a two-dimensional (2D) to a three-dimensional (3D) growth mode. The transition time depends directly upon the growth rate. A detailed discussion is presented to explore the cause of this change in the growth mode.

scholarly journals Prediction Model of Coating Growth Rate for Varied Dip-Angle Spraying Based on Gaussian Sum Model

2016 ◽  
Vol 2016 ◽  
pp. 1-7 ◽  
Author(s):  
Yong Zeng ◽  
Yakun Zhang ◽  
Junxue He ◽  
Hai Zhou ◽  
Chunwei Zhang ◽  
...  
Keyword(s):  
Growth Rate ◽  
Theoretical Model ◽  
Prediction Model ◽  
Coating Thickness ◽  
Least Square ◽  
Programming System ◽  
Gaussian Sum ◽  
Sample Points ◽  
Dip Angle ◽  
Coating Growth

In automatic spraying of spray painting robot, in order to solve the problems of coating growth rate modeling for varied dip-angle spraying technology, a prediction mode of coating growth rate using the Gaussian sum model is proposed. Based on the Gaussian sum model, a theoretical model for coating growth rate with varied dip-angle spraying is established by using the theory of differential geometry. The coating thickness of the sample points in the distribution range of the coating was obtained by making the experiment of varied dip-angle spraying. Based on the theoretical model, the nonlinear least square method is used to fit the coating thickness of the sample points and the parameter values of the theoretical model are calculated. By analyzing the variation law of the parameters with the spray dip-angle, the prediction model of coating growth rate for varied dip-angle spraying is established. Experiments have shown that the prediction model has good fitting precision; it can satisfy the real-time requirement with varied dip-angle spraying trajectory planning in the offline programming system.

Effect of surface kinetics on the step coverage during chemical vapor deposition

1999 ◽  
Vol 14 (6) ◽  
pp. 2377-2380 ◽  
Author(s):  
Gyeong Soon Hwang ◽  
Sang Heup Moon ◽  
Suk Woo Nam ◽  
Chee Burm Shin
Keyword(s):  
Growth Rate ◽  
Chemical Vapor Deposition ◽  
Vapor Deposition ◽  
Numerical Study ◽  
Chemical Vapor ◽  
Surface Kinetics ◽  
Nonlinear Kinetics ◽  
High Tendency ◽  
Step Coverage ◽  
Limited Process

Profile evolution simulations during chemical vapor deposition based on a 2D continuum model reveal that the type of surface kinetics plays an important role in determining step coverage of films deposited in high aspect ratio trenches and vias. Linear surface kinetics, resulting from an adsorption rate limited process, is found to cause difficulty in bringing about conformal step coverage in deep narrow trenches without reducing the growth rate considerably. Under such condition, void-free filling cannot be achieved while maintaining a growth rate acceptable to integrated circuit (IC) manufacturing. The numerical study also suggests that the high tendency of the precursor for chemical equilibrium on a surface, resulting in nonlinear kinetics by a surface reaction limited process, is crucial to achieve a uniform step coverage as typically observed in SiO2 deposition from tetraethylorthosilicate (TEOS).

The characterization of eutectic structures

1973 ◽  
Vol 335 (1600) ◽  
pp. 15-37 ◽  
Keyword(s):  
Growth Rate ◽  
Eutectic Growth ◽  
Growth Behaviour ◽  
Complete Understanding ◽  
The Past ◽  
Limited Success ◽  
Simple Rules ◽  
Unknown Structure ◽  
Made In

Many attempts have been made in the past to bring order to the near-bewildering array of eutectic morphologies. These have met with limited success due mainly to the fact that the morphology of a particular eutectic may be highly dependent on both chemical composition and the rate of freezing. This paper shows for binary alloys, at least, that a more complete understanding of eutectic growth may be obtained by applying a few simple ‘rules’. With these it is possible to so characterize eutectic growth that the unknown structure of a particular eutectic may be prodicted at a given growth rate if the entropy of solution and re­lative volume of each phase are known. The characterization scheme embraces the growth behaviour of the thirty or so systems for which thermodynamic data are more readily available.

Impact of MBE-growth rate on optical properties of AlGaAs/GaAs quantum well structures

1989 ◽  
Vol 5 (2) ◽  
pp. 301-304 ◽  
Author(s):  
Ch. Maierhofer ◽  
S. Munnix ◽  
D. Bimberg ◽  
R.K. Bauer ◽  
D.A. Mars ◽  
...  
Keyword(s):  
Growth Rate ◽  
Optical Properties ◽  
Quantum Well ◽  
Mbe Growth ◽  
Quantum Well Structures

Transport and Chemical Mechanisms in GaN Hydride Vapor Phase Epitaxy

2002 ◽  
Vol 743 ◽  
Author(s):  
Sergey Yu. Karpov ◽  
Alexander S. Segal ◽  
Darya V. Zimina ◽  
Sergey A. Smirnov ◽  
Alexander P. Sid'ko ◽  
...  
Keyword(s):  
Growth Rate ◽  
Vapor Phase ◽  
Growth Conditions ◽  
Vapor Phase Epitaxy ◽  
Hydride Vapor Phase Epitaxy ◽  
Surface Kinetics ◽  
Chemical Mechanisms ◽  
Horizontal Reactor ◽  
Wide Range ◽  
Transport Effects

ABSTRACTOn the basis of both experimental and theoretical studies, a simple quasi-thermodynamic model of surface kinetics is suggested for Hydride Vapor Phase Epitaxy (HVPE) of GaN, working in a wide range of growth conditions. Coupled with detailed 3D modeling of species transport in a horizontal reactor, the model provides quantitative predictions for the GaN growth rate as a function of process parameters. Significance of transport effects on growth rate uniformity is demonstrated.

Dynamics of Mbe Growth Surface Roughening of Ge (001) - A Stochastic Model Study

1990 ◽  
Vol 202 ◽  
Author(s):  
Venkatasubramanian R. Khoie ◽  
Rahim Khoie
Keyword(s):  
Growth Rate ◽  
Surface Roughness ◽  
Electron Diffraction ◽  
Stochastic Model ◽  
Substrate Temperature ◽  
Growth Temperature ◽  
Average Surface Roughness ◽  
Mbe Growth ◽  
Average Surface ◽  
Kinetic Roughening

ABSTRACTA stochastic model for the MBE growth of Ge is developed based on the master equation approach with solid-on-solid restriction and quasi-chemical approximation. The surface kinetic processes included are: adsorption, evaporation and intralayer and interlayer migrations. The growth rate, the average surface roughness and the average intensity of reflection high energy electron diffraction (RHEED) (using kinematical theory of electron diffraction’ were obtained for the MBE growth of Ge with the temperature in the range 100-500°C and a typical flux of 1 Å/sec. The average surface roughness and the growth rate are found to be independent of substrate temperature below 150°C and above 400°C. In the intermediate temperature range, the growth rate increases and the surface roughness decreases with increasing temperature. The kinetic roughening temperature above which a smooth surface remains smooth, is identified from the temperature depen-dance of the average surface roughness and RHEED intensity, as 400°C. The temperature dependance of the average RHEED intensity and the kinetic roughening temperature obtained from this study compare favorably with the experimental results. At low substrate temperature, the surface migration rate is negligible irrespective of the temperature and therefore, the surface roughness and the growth rate become independent of the growth temperature. At high substrate temperatures, the surface roughness and the growth rate attain the limiting values for the flux chosen, owing to the saturation of the available sites for the interlayer migration process. Thus, these parameters become independent of the growth temperature.

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