Raman and photoluminescence spectroscopy of SiGe layer evolution on Si(100) induced by dewetting

Abstract

High temperature annealing of thick (40-100 nm) Ge layers deposited on Si(100) at $400 C leads to the formation of continuous films prior to their transformation into porous-like films due to dewetting. The evolution of Si-Ge composition, lattice strain, and surface morphology caused by dewetting is analyzed using scanning electron microscopy, Raman, and photoluminescence (PL) spectroscopies. The Raman data reveal that the transformation from the continuous to porous film proceeds through strong Si-Ge interdiffusion, reducing the Ge content from 60% to about 20%, and changing the stress from compressive to tensile. We expect that Ge atoms migrate into the Si substrate occupying interstitial sites and providing thereby the compensation of the lattice mismatch. Annealing generates only one type of radiative recombination centers in SiGe resulting in a PL peak located at about 0.7 and 0.8 eV for continuous and porous film areas, respectively. Since annealing leads to the propagation of threading dislocations through the SiGe/Si interface, we can tentatively associate the observed PL peak to the well-known dislocation-related D1 band.

Two-dimensional gersiloxenes with tunable bandgap for photocatalytic H2 evolution and CO2 photoreduction to CO

“…As shown in Fig. 4b, peaks at 281-292 cm −1 , 484-495 cm −1 , and 388-413 cm −1 can be attributed to the phonon modes of Ge−Ge, Si−Si and Ge−Si bonds 44,45 , respectively. Peaks at~640 and~730 cm −1 can be assigned to Si−H bonds 46 , and broad peaks at~2100 cm −1 are assigned to Si−H 2 , which is present only at the sides of silicon nanosheets 46,47 .…”

“…The weak doublet peak at 780 and 845 cm −1 is due to GeH 2 bending modes from neighboring Ge atoms at the edges of each crystalline germanane sheet 24,42 . For Si 6 H 3 (OH) 3 , the bands observed at 519, 640, 876, 1056, 1638, 2116, and 3406 cm −1 correspond to the vibrations of ν(Si-Si), δ(Si-H), ν(Si-OH), ν (Si-O), ν(OH), ν(Si-H), ν((Si3)≡Si-H), and ν(OH) 43,44 , respectively. It can be seen from the FTIR spectrum ( Fig.…”

Dewetting behavior of Ge layers on SiO2 under annealing

“…If the driving force for dewetting is relatively week and the surface morphology transformation begins from defects, the dewetting develops through a gradual propagation along the surface. Such behavior takes place in the structures of Ge/Si(100) 77 – 79 and Si(crystalline)/SiO 2 3 , 41 , 80 – 82 . The dewetting conditions may appear in the structure with the increasing elastic strain in it, as was observed when the thickness of Ge layers on Si(111) was increased at a given substrate temperature 83 .…”

Изменение термодинамических свойств твердого раствора Si-Ge при уменьшении размера нанокристалла

“…Сплав Si−Ge широко используется в современной наноэлектронике, как в качестве гетероструктуры, так и в качестве квантовых точек [1,2]. Вместе с тем термодинамические свойства данного неупорядоченного твердого раствора замещения изучены сравнительно мало, особенно в наноразмерном состоянии.…”