Annealing-induced Ge/Si(100) island evolution

Abstract

Ge/Si(100) islands were found to coarsen during in situ annealing at growth temperature. Islands were grown by molecular-beam epitaxy of pure Ge and annealed at substrate temperatures of T=450, 550, 600, and 650 °C, with Ge coverages of 6.5, 8.0, and 9.5 monolayers. Three coarsening mechanisms operate in this temperature range: wetting-layer consumption, conventional Ostwald ripening, and Si interdiffusion. For samples grown and annealed at T=450 °C, consumption of a metastably thick wetting layer causes rapid initial coarsening. Slower coarsening at longer annealing times occurs by conventional Ostwald ripening. Coarsening of samples grown and annealed at T=550 °C occurs via a combination of Si interdiffusion and conventional Ostwald ripening. For samples grown and annealed at T⩾600 °C, Ostwald ripening of SiGe alloy clusters appears to be the dominant coarsening mechanism.

Microstructural evolution of Ge/Si(100) nanoscale islands

“…Post-growth annealing of the island ensemble should cause the islands to seek this free energy minimum if it existed. The results presented above in Section 3.3.3, and recently discussed elsewhere in more detail [34], seem to rule out this possiblity. Our results indicate that regardless of the growth conditions, the island ensembles will continuously coarsen during post-growth annealing.…”

“…This cluster has a markedly asymmetrical profile with several {1 1 1} stacking faults, and a steeper facet contact angle, corresponding to {1 1 1}, at the left-hand point of contact with the substrate. AFM analyses of samples grown at 700 C has also established the appearance of this type of steep faceting for very large dislocated islands [31] [9], and our detailed AFM analysis of island evolution upon annealing for temperatures in the range of 450-650 C is reported elsewhere [34]. Here we concentrate our attention briefly on samples grown and annealed at 650 C, and having Ge coverages of 6.5, 8.0 and 9.5 ML.…”

“…These observations of island morphology after annealing are consistent with the results of AFM studies (see, for example, Refs. [9,34]), which showed a significant island coarsening (Ostwald ripening) due to annealing at the growth temperature T ¼ 650 C.…”

Real-time coarsening dynamics of Ge∕Si(100) nanostructures

“…These include Si interdiffusion and decay of a metastably thick wetting layer. 7,8 Island-island elastic interactions may accelerate Ostwald ripening if the island density is high enough 9 and hut clusters with elongated bases have been shown to be less stable than square-based pyramids. 10 Here, we present a quantitative analysis of mixed pyramid/hut ensemble coarsening during growth temperature annealing using real-time, in situ elevated temperature scanning tunneling microscopy.…”

Early stage of heteroepitaxial Ge growth on Si(100) substrate with surface treatments using inductively coupled plasma (ICP)

“…특히, Si CMOS IC와의 호환성과 더불어 초고속, 고응답성 등의 장점을 겸비하는 신소자 기반기술, 광통신, 광컴퓨터, 센 서 등 다양한 응용 분야에서 매우 중요한 이슈로 대두되 고 있다 [11,12]. 게다가 Ge의 경우 GaAs와 비슷한 결 정 격자 상수와 열팽창 계수를 가지고 있기 때문에 Si 기판 위에 성장된 Ge 층의 경우 GaAs와 같은 광활성층 과의 연속 성장이 가능하다 [14,15]. Ge 층은 Si과 GaAs 결과이다.…”