Stranski-Krastanow islanding initiated on the stochastic rough surfaces of the epitaxially strained thin films

Journal Article · Sat Jun 14 00:00:00 EDT 2014 · Journal of Applied Physics

DOI:https://doi.org/10.1063/1.4883295· OSTI ID:22304124

Celik, Aytac ^[1]; Emre Oren, Ersin ^[1]

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1. Department of Biomedical Engineering, TOBB University of Economics and Technology, 06560 Ankara (Turkey)

Quantum dots (QD) have discrete energy spectrum, which can be adjusted over a wide range by tuning composition, density, size, lattice strain, and morphology. These features make quantum dots attractive for the design and fabrication of novel electronic, magnetic and photonic devices and other functional materials used in cutting-edge applications. The formation of QD on epitaxially strained thin film surfaces, known as Stranski-Krastanow (SK) islands, has attracted great attention due to their unique electronic properties. Here, we present a systematic dynamical simulation study for the spontaneous evolution of the SK islands on the stochastically rough surfaces (nucleationless growth). During the development of SK islands through the mass accumulation at randomly selected regions of the film via surface drift-diffusion (induced by the capillary and mismatch stresses) with and/or without growth, one also observes the formation of an extremely thin wetting layer having a thickness of a few Angstroms. Above a certain threshold level of the mismatch strain and/or the size of the patch, the formation of multiple islands separated by shallow wetting layers is also observed as metastable states such as doublets even multiplets. These islands are converted into a distinct SK islands after long annealing times by coalescence through the long range surface diffusion. Extensive computer simulation studies demonstrated that after an initial transient regime, there is a strong quadratic relationship between the height of the SK singlet and the intensity of the lattice mismatch strain (in a wide range of stresses up to 8.5 GPa for germanium thin crystalline films), with the exception at those critical points where the morphological (shape change with necking) transition takes place.

• OSTI ID: 22304124
• Journal Information: Journal of Applied Physics, Vol. 115, Issue 22; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA); ISSN 0021-8979
• Country of Publication: United States
• Language: English

Related Subjects

75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
ANNEALING
CAPILLARIES
COMPUTERIZED SIMULATION
CRYSTAL DEFECTS
DIFFUSION
ENERGY SPECTRA
EPITAXY
GERMANIUM
LAYERS
MASS
METASTABLE STATES
QUANTUM DOTS
RANDOMNESS
STOCHASTIC PROCESSES
STRAINS
STRESSES
SURFACES
THICKNESS
THIN FILMS
TRANSIENTS