Abstract
The comprehensive investigation of the effect of growth parameters on structural and optical properties of Si-based single layer Ge nanoislands grown via Stranski-Krastanov mechanism employing radio frequency magnetron sputtering due to its high deposition rate, easy procedure, economical cost, and safety is carried out. The estimated width and height of Ge nanoislands produced by this technique are in the range of ∼8 to ∼30 and ∼2 to 8 nm, respectively. Varieties parameters are manipulated to optimize the surface morphology and structural and optical behavior of Ge nanoislands. The resulted nanoislands are analyzed using various analytical techniques including atomic force microscope, X-ray diffraction, energy dispersive X-ray spectroscopy, room temperature photoluminescence, and Raman spectroscopy. The optimum parameters for growing high quality samples having high number density and homogenous and small size distribution are found to be 400°C for substrate temperature, 300 sec for deposition time, 10 sccm for Ar flow, and 100 W for radio frequency power. The excellent features of the results suggest that our systematic investigation on the organized growth factors and their effects on surface parameters and photoluminescence emission energy may constitute a basis for the tunable growth of Ge nanoislands (100) nanoislands suitable in nanophotonics.
Highlights
Due to the lattice mismatch of 4.2% the Ge nanoislands spontaneously formed on Si substrate through StranskiKrastanov (SK) growth mode, the SK model assumes that an elastically strained wetting layer grows on a latticemismatched substrate to a certain thickness; additional deposition leads to growth of three dimensional islands on top of the film
To the best of our knowledge the compressive analysis of all the possible growth parameters dependent on surface morphology and optical behavior of Ge nanoislands has not been clearly demonstrated, and we report it for the first time
atomic force microscope (AFM) (SPI3800) built by Seiko Instrument Inc. (SII) and X-ray diffraction (XRD) (Bruker D8 Advance Diffractometer) using Cu-Kα1 radiations (1.540 Å) at 40 kV and 100 mA are used for growth morphology characterization of samples
Summary
Due to the lattice mismatch of 4.2% the Ge nanoislands spontaneously formed on Si substrate through StranskiKrastanov (SK) growth mode, the SK model assumes that an elastically strained wetting layer grows on a latticemismatched substrate to a certain thickness; additional deposition leads to growth of three dimensional islands on top of the film. Nanosizing expands the energy-band gap and changes them into pseudo-direct-gap semiconductor which is expected to adjust these disadvantages to use these materials for optoelectronic devices. For conjunction of such optical compound semiconductors, especially the narrow-gap ones around the optical communication wavelength (∼0.8 eV) with Si due to their large lattice mismatch, there are fundamental difficulties. Germanium displays good congeniality with Si. In contrast, germanium displays good congeniality with Si In this framework, self-assembled nanostructures of Ge on Si substrates have been widely studied as a promising candidate toward Si-based optoelectronics applications [1, 2]
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