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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]

The issues pertaining to non-uniform sputtering from polycrystalline grains in metal thin films during Secondary Ion Mass Spectrometer depth profiling process are investigated. A case study on Mo thin films obtained through magnetron sputter deposition at different substrate temperatures and possessing different microstructural features is presented. X-ray diffraction, scanning electron microscopy, Rutherford backscattering spectrometry and atomic force microscopy were used to elucidate and corroborate the experimental observations of diffusion like broadening observed in the SIMS profiles. While the interfacial diffusion is ruled out based on the inferences derived from complementary experimental investigations, the observed broadening could be attributed to the influence of microstructural features on the sputtering process. [ABSTRACT FROM AUTHOR]

Ion beam sputter deposition of AlN thin films to different time scales was carried out in reactive assistance of N + /N 2 + ions. The incipient stages of the growth morphology were characterized using atomic force microscopy. Dynamic scaling theory was invoked to analyze the evolution of surface roughness and the growth mechanism therein. Two distinct exponents ‘ α ’ (static) and ‘ β ’ (dynamic) were used to unravel the film growth characteristics. Our results show that as the deposition time ( t ) increases, ‘ α ’ decreases gradually and substrate surface coverage increases indicated by a decrease in critical length Lc. Dynamic scaling exponent ‘ β ’ was estimated to be 0.36 for the deposition from isolated nuclei to full surface coverage of the substrate. During the growth, rms roughness of the film was increased from 1.99 to 3.42 nm as the deposition time was increased from 3 min to 15 min. Surface diffusion becomes the major roughening phenomenon while bulk diffusion subside it at each stage by smoothening to yield corresponding rms roughness. [ABSTRACT FROM AUTHOR]

We report the synthesis of polycrystalline ( poly )-SiGe alloy thin films through solid state reaction of Si/Ge multilayer thin films on Si and glass substrates at low temperature of 500 °C. The pristine thin film was deposited using electron beam evaporation with optimized in-situ substrate heating. Our results show the co-existence of amorphous Si ( a -Si) phase along with the poly -SiGe phase in the pristine thin film. The a -Si phase was found to subsume into the SiGe phase upon post deposition annealing in the temperature range from 600° to 800 °C. Additionally, dual energy band gaps could be observed in the optical properties of the annealed poly -SiGe thin films. The stoichiometric evolution of the pristine thin film and its subsequent effect on the band gap upon annealing are discussed on the basis of diffusion characteristics of Si in poly -SiGe. [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]

In this work, electrical and optical properties of large-grained Ge rich polycrystalline (poly) - SiGe alloy thin film grown via Al induced layer exchange (ALILE) crystallization process are reported. The ALILE process results in inevitable p -type doping of the poly -SiGe film. The concentration of holes in the film (~ 7 × 1019 cm−3) was large to the extent that degenerate effects became prominent in the thin film's electrical behavior. The high crystalline quality of the poly -SiGe thin film is elucidated by the large value of Hall mobility ~ 260 cm2 V−1 sec−1 in the temperature range from 4 to 50 K. The degenerate doping of the poly -SiGe thin film also impacts the film's optical absorption coefficient. There is a blue shift in the absorption edge, indicating an apparent increase in the optical band-gap due to the Burstein-Moss shift. Also, there is an increase in absorption coefficient in the NIR region due to free carrier absorption. • ALILE grown Ge rich poly-SiGe thin film at 350 °C is degenerately doped and shows p -type conductivity. • Low resistivity and high mobility are achieved. • Degenerate doping leads blue shifting in optical band gap. • The degenerate film may be a suitable candidate for p+ layer is back surface field solar cell. [ABSTRACT FROM AUTHOR]