Enhanced optical properties of Si1−xGex alloy nanocrystals in a planar microcavity

Abstract

The emission properties of Si 1Ϫx Ge x alloy nanocrystals (nc-Si 1Ϫx Ge x) in an optical microcavity were studied, and the results were compared with those of nc-Si in the same structure. The cavity consists of two distributed Si/SiO 2 Bragg reflectors ͑DBRs͒ sandwiching a thin SiO 2 film containing nc-Si 1Ϫx Ge x. The commonly observed cavity effects, that is, spectral narrowing, high directionality, and photoluminescence ͑PL͒ enhancement in the normal direction, were observed. In nc-Si 1Ϫx Ge x , PL lifetime was lengthened by cavity formation, while that of nc-Si was shortened. This difference is due to the different dielectric contrast between active layers and DBRs.

Microcavity effects in SiGe/Si heterogeneous nanostructures prepared by electrochemical anodization of SiGe/Si multiple quantum wells

“…1(c), the porous SiGe/Si HNRs have lower refractive indices (1.93 for Si and 2.25 for SiGe in wavelengths from 600 to 700 nm) than that in bulk Si (3.75). 13,14 Therefore, the two interfaces, the sample surface, and the interface between porous SiGe/Si and Si substrates could be treated as mirrors that form an optical cavity.…”

“…From the best fit of the experimental data, the parameters obtained are n ¼ 2.68 and b ¼ 1:36 Â 10 À4 K À1 (at 300 K), which are very close to the previous reports. 14,25 Therefore, it can be concluded that the temperature-induced refractive index change in the SiGe/Si HNR is the main factor that is responsible for the thermal variation in the resonator behavior.…”

Room-temperature light-emission from Ge quantum dots in photonic crystals

“…However, it is difficult to fabricate efficient light-emitting devices based on silicon due to the indirect bandgap. The quantum effect is utilized to enhance the radiative recombination of excited carriers by confining the carriers in nano-sized structures, such as quantum wells [1,2], quantum dots [3][4][5][6], and nanocrystals [7,8]. In various Si-based quantum structures, Ge self-assembled quantum dots [3][4][5][6] were intensively studied since the easy fabrication and light-emission in telecommunication wavelength range.…”

Generation and Wavelength Control of Resonant Luminescence from Silicon Photonic Crystal Microcavities with Ge Dots

“…They include nanostructures such as quantum wells, [1][2][3] quantum dots, [4][5][6][7][8][9] and nanocrystals. [10][11][12] Among these structures, Ge self-assembled quantum dots have been intensively studied in recent years. Ge self-assembled quantum dots can be grown easily on silicon wafers in Stranski-Krastanov (SK) mode.…”