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The present study reports Al induced crystallization of amorphous (a)-SiGe in the Al-Ge-Si ternary system with the a-SiGe/Al bilayer structure on glass at low temperature ∼350 °C. The origin of the Al induced layer exchange (ALILE) mechanism that occurs in the a-SiGe/Al system is investigated by studying the crystallization kinetics as well as the evolution of stress in the Al layer during the crystallization process. The growth kinetics was analyzed using Avrami's theory of phase transformation as the crystallization occurs under isothermal condition. It shows that initial growth of the polycrystalline (poly)-SiGe phase follows a 3D mode, characterized by n ∼ 3, where n is the Avrami constant. It then switched over to a 2D mode through an intermediate explosive growth as the crystallization fraction increases. The stress was evaluated using X-ray diffraction analysis based on multi-hkl sin2 ψ formalism. A corroboration of the growth kinetics with stress analysis shows that nucleation and growth of the poly-SiGe phase inside the Al layer at 350 °C leads to buildup of compressive strain in the Al layer. The increase in strain energy due to compression in the Al layer at elevated temperature is the driving force that initiates the layer exchange process. [ABSTRACT FROM AUTHOR]

Au (metal) induced layer exchange and crystallization of amorphous Si ( a -Si) on corning glass (CG) in a -Si/Au/CG thin film specimen upon vacuum annealing (~ 10 − 8 mbar) is reported. The crystallization characteristics of these specimens at temperatures ranging on either side of the Au-Si eutectic temperature T e (Au-Si) are investigated. Our results shows that solid state diffusion assisted layer exchange of the a -Si and Au layer, followed by crystallization of a -Si into crystalline Si ( c -Si) occur at 350 °C (below the T e ). The upper limit to this crystallization mechanism was observed to be above the T e (Au-Si) and this continues till ~ 400 °C in the present study. Above this limit, the layer exchange phenomenon ceases and eutectic mixing reaction of Au-Si takes over to form diffusion limited crystalline aggregates of Si with different microstructural attributes. [ABSTRACT FROM AUTHOR]

• Large grain Ge rich polycrystalline SiGe thin film on glass at 350 °C using Al-induced layer exchange crystallization. • Degenerate p -type doping from residual Al atoms. • Weak anti-localization effect below 10 K in magnetoresistance. We report the low-temperature magneto-transport properties of a polycrystalline-SiGe thin film realized on glass at 350 ℃ via Al-induced layer exchange crystallization. The film exhibits a degenerate p -type behavior, and we observed evidence of weak-antilocalization (WAL) effect that manifests as an anomalous positive magnetoresistance (MR) below 10 K and weak magnetic fields (B) between ± 1 Tesla. While the spin–orbit coupling length is nearly constant at ~ 40 nm, the temperature dependence of phase-coherence length, which has a maximum value at 4 K (~131 nm), indicates hole-hole scattering as the predominant de-phasing mechanism. This result shows the degenerate Al doping causes the WAL effect in the present system. [ABSTRACT FROM AUTHOR]

• Polycrystalline Ge thin film on glass at ~170 °C using Au induced layer exchange. • Complete exchange of the Ge/Au bilayer facilitates effective removal of Au layer. • Role of the interface thermodynamics and energetics in the crystallization. • The film exhibits p -type behaviour due to point defects induced acceptor states. • Investigation on the mobility limiting mechanism. We report the realization of polycrystalline (poly)-Ge thin film on glass (insulator) at a significantly low temperature of ~170 °C. We realized it using Au induced layer exchange crystallization scheme in a thin film stack having amorphous (a)-Ge/GeO x /Au/glass structure. The observed crystallization temperature is one of the lowest values reported in the literature. The paper also discusses the interface energetics that drives the crystallization in detail. Au has an extremely low solubility of ~1.3 × 107 cm−3 in Ge at this low processing temperature. The layer exchange process facilitates an effective etching of the Au layer, resulting in a poly -Ge thin film free of contamination from residual Au impurities within EDS's sensitivity. However, the poly -Ge thin film exhibits a p -type semiconducting behavior, with a moderate doping concentration of ~1.3 × 1017 cm−3 , and a low resistivity ~1 Ω cm at RT due to point defects induced acceptor states. The thin film showed a mobility ~50 cm2 V−1-s−1 at RT, highest for a poly -Ge thin film formed at such low temperature. The temperature dependence of mobility indicates a high barrier of ~84 meV at the grain boundaries, which serve as the main scattering mechanism limiting the carrier conduction. [ABSTRACT FROM AUTHOR]