Ultrathin Si_mGe_nstrained layer superlattices-a step towards Si optoelectronics

Abstract

Ultrathin Si , Ge, (m monolayers (ML) si, n ML Ge) strained layer superlattices (SE) have been grown by molecular beam epitaxy. The optical properties of these structures depend on the concept of band-structure engineering by Brillouin zone folding and Strain adjustment of the SLS by a Si, _, , Ge, , alloy buffer layer. The energies and the oscillator strengths of the bandgap and Intersubband transitions have been studied theoretically for Si , Ge, SLS with a variety of period lengths, particularly those of m + n = I O . Various characterization tools such as x-ray diffraction, transmission electron microscopy Raman spectroscopy, photoluminescence (PL) and photocapacitance measurements have been used to analyse growth quality, interface sharpness morphology. strain distribution and optical properties of the superlattice experimentally. The PL data indicative of the quasidirect energy gap of the 10 ML strain-symmetrized SLS in the near-infrared spectral regime (hv -0.8eV) are presented and discussed as well as complementary photocapacitance measurements on a p-n doped Si ,Ge, SLS diode. The fabrication of test mesa diodes from Si/Ge SLS structures is described. Finally. device applications olfering the possibility of monolithic integration of Superlattice devices with complex silicon-based electronic circuits are outlined. Material K (W m K -' ) Si 145 GaAs 46 Diamond 2000 Copper 384

Si/SiGe Heterointerfaces in One-, Two-, and Three-Dimensional Nanostructures: Their Impact on SiGe Light Emission

“…Hence, it was thought that light sources based on the zone-folding concept were unlikely to produce useful devices. It was predicted that these atomic layer superlattices would be more likely to find ultimate use as infrared detectors instead of as light emitters (Presting et al, 1992b;Pearsall, 1994).…”

Growth, Quantum Confinement and Transport Mechanisms of Ge Nanodot Arrays Formed on a SiO2 Monolayer

“…In contrast, germanium shows good congeniality with Si. In this context, self-assembled nanostructures of Ge on Si substrates have been extensively studied as a promising candidate toward Si-based optoelectronics applications [1,2].…”

Miniband-related 1.4–1.8 μm luminescence of Ge/Si quantum dot superlattices

“…The development of epitaxial methods enabled the growth of ultra-thin Ge/ Si layer superlattices. Structures which are based on the Brillouin folding concept can result in a quasi-direct optical transitions near 1.55-lm wavelength [1][2][3][4]. However, due to the small localization potential the photoluminescence (PL) from Ge/Si layer superlattices is observed only at low temperatures [3][4][5][6].…”