Growth Monitoring with Submonolayer Sensitivity Via Real-Time Thermal-Conductance Measurements
Ferrando-Villalba, Pablo (Universitat Autònoma de Barcelona. Departament de Física)
Takegami, Daisuke (Universitat Autònoma de Barcelona. Departament de Física)
Abad, Llibertat (Institut de Microelectrònica de Barcelona)
Ràfols-Ribé, Joan (Universitat Autònoma de Barcelona. Departament de Física)
Lopeandía Fernández, Aitor (Universitat Autònoma de Barcelona. Departament de Física)
García, Gemma (Universitat Autònoma de Barcelona. Departament de Física)
Rodríguez-Viejo, Javier (Universitat Autònoma de Barcelona. Departament de Física)

Data:	2019
Resum:	Growth monitoring during the early stages of vapor deposition is of prime importance to understand the growth process, the microstructure, and thus the overall layer properties. We demonstrate that phonons can be used as an extremely sensitive probe to monitor the real-time evolution of film microstructure during growth, from incipient clustering to continuous film formation. For that purpose, a silicon nitride membrane-based sensor is fabricated to measure the in-plane thermal conductivity of thin film (conductive or nonconductive) samples. Operating with the 3ω-Völklein method at low frequencies, the sensor shows an exceptional resolution down to Δ(κt)=0. 065W/mKnm, enabling accurate measurements even in poor conductive samples. Validation of the sensor performance is done by growth characterization of organic and metallic thin films to tackle the low to high thermal-conductivity range. In both cases, at early stages of growth, the extreme sensitivity of the technique has revealed an initial reduction of the effective thermal conductance of the supporting amorphous membrane, K, related to the surface phonon scattering enhanced by the incipient nanoclusters formation. As cluster coalescence advances, K reaches a minimum to rise up upon the percolation threshold. Subsequent island percolation produces a sharp increase of the conductance and once the surface coverage is completed K increases linearly with thickness. The thermal conductivity of the deposited films is also obtained from the slope of K with thickness.
Ajuts:	Ministerio de Economía y Competitividad MAT2016-79579-R Ministerio de Economía y Competitividad FIS2013-50304-EXP Ministerio de Economía y Competitividad RyC-2013-12640
Drets:	Aquest document està subjecte a una llicència d'ús Creative Commons. Es permet la reproducció total o parcial, la distribució, la comunicació pública de l'obra i la creació d'obres derivades, fins i tot amb finalitats comercials, sempre i quan es reconegui l'autoria de l'obra original.
Llengua:	Anglès
Document:	Article ; recerca ; Versió publicada
Matèria:	Accurate measurement ; Amorphous membranes ; Cluster coalescence ; Film microstructures ; Growth characterization ; Percolation thresholds ; Silicon nitride membrane ; Thermal conductance
Publicat a:	Physical review applied, Vol. 12, Issue 1 (July 2019) , art. 14007, ISSN 2331-7019

DOI: 10.1103/PhysRevApplied.12.014007

11 p, 1.1 MB

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