Photoluminescence of Si/Ge nanostructures grown by molecular-beam epitaxy at low temperatures

10.1007/s11453-008-1009-x

“…The formation of macroclusters for the Si 1 -x Ge x layers thicker than 5 a also leads to the emergence of low-intensity peaks in the energy range 0.75-0.85 eV. The third spectral region with a clearly pronounced narrow peak with the energy 1.1 eV is attributed to recombination of bound excitons with emission of a transverse optical phonon in the Si substrate [1][2][3][4][5][6].…”

“…One of the types of nanodimensional structures which are now widely used is Si/Ge nanostructures. Discovery of efficient electroluminescence in the wavelength region 1.5 µ m in these structures stimulated their intense study in view of possible fabrication of light-emitting devices for fiber-optics communication systems, which are easily integrated with the Si technology of fabrication of integrated microcircuits [1][2][3][4][5][6]. In addition, it was found that the periodic Si/Si 1 -x Ge x superlattices can be used for the development of nanoelectronic devices whose operation is based on the effect of resonance tunneling of electrons [7,8].…”

“…Deposition of the Ge layers on (001) Si leads, depending on technological modes, to the formation of elastically stressed Si 1 -x Ge x nanolayers or self-assembly of Si 1 -x Ge x islands of various shapes, namely, pyramidal clusters or dome clusters [1][2][3][4][5][6]. The absence of dislocations at the material interfaces, manifestation of the quantum-size effect, and the possibility of realization of quasi-direct band-to-band transitions of localized charge carriers make these structures very promising for optoelectronics.…”

“…Experimental investigations showed that the photoluminescence (PL) spectrum of the Si/Si 1 -x Ge x nanostructures includes several peaks with the energies 0.75-0.85, 0.9-1.05, and 1.1 eV, which is characteristic of several recombination channels [1,2]. However, ambiguity of interpretation of emergence of these peaks in various reports [3][4][5][6] and the necessity of determination of parameters of the structure in order to increase the efficiency of emission of light require theoretical study of recombination processes in the Si/Si 1 -x Ge x nanostructures.…”

Characterization of the local structure of Ge quantum dots by X-ray absorption

“…The properties of Si/Ge/Si structures, Si/Ge superlattices and SiGe/Si-heterostrustures were studied most actively by the methods of electron and atomic-force microscopy (AFM) [4][5][6][7][8][9][10][11][12], X-ray absorption fine structure (XAFS) [13,14], photoluminescence (PL) [5][6][7][8][15][16][17][18][19][20][21][22], RHEED [20], scanning tunneling microscopy (STM) [23], Auger electron spectroscopy (AES) [24] and Raman scattering [5,20,[25][26][27][28][29]. Nevertheless, there are some questions without answers concerning understanding and controlling the morphology of interface particularly in the buried layers.…”