Atomic Force Microscopy Study of GaN Grown on Al2O3(0001) by LP-MOVPE

2000 ◽  
Vol 639 ◽  
Author(s):  
K. Xu ◽  
D. H. Lim ◽  
B. L. Liu ◽  
X. L. Du ◽  
G. H. Yu ◽  
...  
Keyword(s):  
Atomic Force Microscopy ◽  
Growth Temperature ◽  
Spiral Growth ◽  
Initial Growth ◽  
Growth Mechanisms ◽  
Remarkable Effect ◽  
Force Microscopy ◽  
Step Flow ◽  
Atomic Force ◽  
Step Flow Growth

ABSTRACTThere is currently a high degree of interest in understanding the diverse mechanisms that determine the growth morphology of epitaxial films. To understand and control over these mechanisms, it is essential to know how the growth mechanisms are correlated with morphologies. In GaN MOVPE processes, growth temperature has a remarkable effect on the film morphologies and properties. In present work, the temperature dependency of surface morphology of GaN epilayers grown by low-pressure metal-organic vapor phase epitaxy (LP-MOVPE) was studied using atomic force microscopy. It was demonstrated that dislocations strongly influence the growth mechanisms and the morphology of the films. Three growth modes were identified at different growth temperature ranged from 1030°C to 1100°C, which are, (1) spiral growth dominated by dislocation with screw type, (2) monolayer step flow, and (3) nucleation-assisted step flow growth. The significant effect of dislocation on the surface morphologies and growth mechanisms may be attributed to the high dislocation density and higher activation energy for a step overcoming the dislocation pinning in GaN. Because few dislocations will be introduced under monolayer step flow growth mode, we can infer the useful information about GaN initial growth.

The Initial Stages of Growth of Ordered GaInP and GaInAs Grown by Metal Organic Vapor Phase Epitaxy

1999 ◽  
Vol 583 ◽  
Author(s):  
M. C. Hanna ◽  
A. Mascarenhas ◽  
Hyeonsik M. Cheong
Keyword(s):  
Raman Spectroscopy ◽  
Atomic Force Microscopy ◽  
Direct Evidence ◽  
Force Microscopy ◽  
Step Flow ◽  
Organic Vapor ◽  
Stages Of Growth ◽  
Atomic Force ◽  
Metal Organic ◽  
Step Flow Growth

AbstractWe have used atomic force microscopy (AFM) and Raman spectroscopy to investigate the development of the surface morphology of (001) direct and vicinal GaInP and GaInAs grown under conditions to produce strong CUPtB ordering. Raman spectroscopy provided direct evidence of CuPtB ordering in layers as thin as 10 nm for GaInP and 5 nm for GaInAs. We find that the morphology of GaInP and GaInAs on (001)6B substrates consists of ridges, which are aligned predominately along the [110] direction (A-direction). These ridges are well developed even at layer thicknesses of 2 nm, and their sides consist of step-bunches and near (001) terraces. On (001) direct substrates, the GaInP morphology is similar to that obtained on 6B substrates, although the step bunches have no preferential orientation, while GaInAs (001) growth proceeds by a combination of 2D-island and step flow growth. We discuss possible reasons for the differences in the morphology of ordered GaInP and GaInAs. The results of this work suggest it may be difficult to produce abrupt heterointerfaces in structures containing ordered GalnP and GaInAs alloys.

Development of Cross-Hatch Morphology During Growth of Lattice Mismatched Layers

2001 ◽  
Vol 673 ◽  
Author(s):  
A. Maxwell Andrews ◽  
J.S. Speck ◽  
A.E. Romanov ◽  
M. Bobeth ◽  
W. Pompe
Keyword(s):  
Misfit Dislocation ◽  
Film Growth ◽  
Strain Relaxation ◽  
Dislocation Generation ◽  
Force Microscopy ◽  
Step Flow ◽  
Atomic Force ◽  
Subsequent Step ◽  
Step Flow Growth ◽  
Lateral Scale

ABSTRACTAn approach is developed for understanding the cross-hatch morphology in lattice mismatched heteroepitaxial film growth. It is demonstrated that both strain relaxation associated with misfit dislocation formation and subsequent step elimination (e.g. by step-flow growth) are responsible for the appearance of nanoscopic surface height undulations (0.1-10 nm) on a mesoscopic (∼100 nm) lateral scale. The results of Monte Carlo simulations for dislocation- assisted strain relaxation and subsequent film growth predict the development of cross-hatch patterns with a characteristic surface undulation magnitude ∼50 Å in an approximately 70% strain relaxed In0.25Ga0.75As layers. The model is supported by atomic force microscopy (AFM) observations of cross-hatch morphology in the same composition samples grown well beyond the critical thickness for misfit dislocation generation.

Ex situ atomic force microscopy studies of growth mechanisms of cadmium mercury thiocyanate crystals

2002 ◽  
Vol 234 (2-3) ◽  
pp. 480-486 ◽  
Author(s):  
X.N. Jiang ◽  
D. Xu ◽  
D.L. Sun ◽  
D.R. Yuan ◽  
M.K. Lu ◽  
...  
Keyword(s):  
Atomic Force Microscopy ◽  
Ex Situ ◽  
Growth Mechanisms ◽  
Force Microscopy ◽  
Atomic Force

4H-SiC Homoepitaxial Growth on Substrates with Different Off-Cut Directions

2011 ◽  
Vol 679-680 ◽  
pp. 55-58 ◽  
Author(s):  
Birgit Kallinger ◽  
Bernd Thomas ◽  
Patrick Berwian ◽  
Jochen Friedrich ◽  
Gerd Trachta ◽  
...  
Keyword(s):  
Growth Process ◽  
Screw Dislocations ◽  
Force Microscopy ◽  
Step Flow ◽  
Homoepitaxial Growth ◽  
Atomic Force ◽  
P Type ◽  
Step Flow Growth ◽  
Edge Dislocations ◽  
Doping Range

Homoepitaxial growth on 4° off-axis substrates with different off-cut directions, i.e. [11-20] and [1-100], was investigated using a commercial CVD reactor. The characteristics of the growth process on substrates with different off-cut directions were determined with respect to applicable C/Si ratio, growth rate and n- and p-type doping range. Stable step flow growth was achieved over a broad range of C/Si ratio at growth rates ~ 15 µm/h in both cases. The n-type doping level of epilayers can be controlled at least in the range from 5  1014 cm-3 to 3  1017 cm-3 on both types of substrates. Highly p-type epilayers with p = 2  1019 cm-3 can also be grown on [1-100] off-cut substrates. Hence, the growth process for standard substrates was successfully transferred to [1-100] off-cut substrates resulting in epilayers with similar doping levels. The dislocation content of the grown epilayers was investigated by means of defect selective etching (DSE) in molten KOH. For both off-cut directions of the substrates, similar densities of threading edge dislocations (TED), threading screw dislocations (TSD) and basal plane dislocations (BPD) were found in the epilayers. Epilayers with very low BPD density can be grown on both kinds of substrates. The remaining BPDs in epilayers are inclined along the off-cut direction of the substrate. The surface morphology and roughness was investigated by atomic force microscopy (AFM). The epilayers grown on [1-100] off-cut substrates are smoother than those on standard substrates.

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