Nanotube self-organization: Formation by step-flow growth

AbstractWe describe three different aspects of the self-organization of steps and domain boundaries of a 7×7 reconstruction on SI(111) surfaces. The first is the formation of a triangular-tiled pattern of “1×1’ and 7×7 domains during the phase transition. ‘1÷1’ and 7×7 domains have different surface stresses. The triangular-tiled pattern is stabilized through stress relaxation. The second is the step arrangement inside a hole, which was fabricated by a standard lithographic technique. The step arrangement in the hole depends on the temperature. Below the ‘1×1’-to-7×7 phase transition, the hole has a three-fold symmetry consisting of step-bunched and non-bunched regions. This is because the step arrangement on the vicinal Si(111) surfaces depends on the direction of the steps. The third aspect is the formation of a pattern of steps and domain boundaries induced by Si growth. During the step-flow growth on Si(111), steps preferentially protrude along the domain boundaries on the lower terrace. The resulting changes in step shape induce a unique rearrangement of the domain boundaries, the number of which decreases during growth. However, when a periodic pattern is formed in the initial stages, it remains stable during growth.

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Temperature-Dependent Photoluminescence of ZnO Thin Films Grown on Off-Axis SiC Substrates by APMOCVD

Materials ◽

10.3390/ma14041035 ◽

2021 ◽

Vol 14 (4) ◽

pp. 1035

Author(s):

Ivan Shtepliuk ◽

Volodymyr Khranovskyy ◽

Arsenii Ievtushenko ◽

Rositsa Yakimova

Keyword(s):

Optical Properties ◽

Structural Quality ◽

Organic Chemical ◽

Zno Films ◽

Vicinal Surfaces ◽

Temperature Dependent ◽

Step Flow ◽

Step Flow Growth ◽

First Time ◽

Temperature Dependent Photoluminescence

The growth of high-quality ZnO layers with optical properties congruent to those of bulk ZnO is still a great challenge. Here, for the first time, we systematically study the morphology and optical properties of ZnO layers grown on SiC substrates with off-cut angles ranging from 0° to 8° by using the atmospheric pressure meta–organic chemical vapor deposition (APMOCVD) technique. Morphology analysis revealed that the formation of the ZnO films on vicinal surfaces with small off-axis angles (1.4°–3.5°) follows the mixed growth mode: from one side, ZnO nucleation still occurs on wide (0001) terraces, but from another side, step-flow growth becomes more apparent with the off-cut angle increasing. We show for the first time that the off-cut angle of 8° provides conditions for step-flow growth of ZnO, resulting in highly improved growth morphology, respectively structural quality. Temperature-dependent photoluminescence (PL) measurements showed a strong dependence of the excitonic emission on the off-cut angle. The dependences of peak parameters for bound exciton and free exciton emissions on temperature were analyzed. The present results provide a correlation between the structural and optical properties of ZnO on vicinal surfaces and can be utilized for controllable ZnO heteroepitaxy on SiC toward device-quality ZnO epitaxial layers with potential applications in nano-optoelectronics.

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Growth of (Zn)CdSe quantum structures on vicinal GaAs(001) substrates: step flow growth versus strain effects

Journal of Crystal Growth ◽

10.1016/s0022-0248(00)00162-7 ◽

2000 ◽

Vol 214-215 ◽

pp. 606-609 ◽

Cited By ~ 5

Author(s):

T Passow ◽

H Heinke ◽

D Kayser ◽

K Leonardi ◽

D Hommel

Keyword(s):

Quantum Structures ◽

Strain Effects ◽

Step Flow ◽

Step Flow Growth ◽

Versus Strain

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

MRS Proceedings ◽

10.1557/proc-673-p5.2 ◽

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.

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