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Title: Crystallization kinetics of ultrathin amorphous Si film induced by Al metal layer under thermal annealing and pulsed laser irradiation

Abstract

The crystallization kinetics of ultrathin a-Si induced by Al under thermal annealing and pulsed laser irradiation has been studied. Under thermal annealing, the crystallization temperature and activation energy for crystallization of a-Si with a thin Al metal layer was reduced to around 340 degree sign C and 3.3 eV, respectively. The reaction exponent was determined to vary from 1.5 to 1.8, corresponding to a crystallization process in which grain growth occurs with nucleation, and the nucleation rate decreases with the progress of grain growth. Under high power pulsed laser irradiation, the crystallization and reamorphization of a-Si were found to take place sequentially in a-Si/Al. The reamorphization of a-Si in contact with a thin Al metal layer can be attributed to the melting of a-Si/Al initiated at the interface, due to the low melting temperature of Si-Al alloy and the rapid solidification that followed. Considering only the crystallization process, the activation energy for crystallization of a-Si induced by Al, estimated to be about 0.22 eV, was nearly an order of magnitude lower than that under thermal annealing. This may be explained by the explosive crystallization of a-Si by mechanical impact with a high power pulsed laser. In the meantime, the reactionmore » exponent, determined to range from 1.9 to 2.2, was slightly higher than that under thermal annealing, indicating that the decrease of nucleation rate with the progress of grain growth during crystallization was slower, and the crystallization process became more nucleation dominant.« less

Authors:
;  [1]
  1. Department of Materials Engineering, National Chung Hsing University, Taichung, Taiwan 40254 (China)
Publication Date:
OSTI Identifier:
20982702
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 101; Journal Issue: 4; Other Information: DOI: 10.1063/1.2654512; (c) 2007 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; ACTIVATION ENERGY; ALUMINIUM; ALUMINIUM ALLOYS; AMORPHOUS STATE; ANNEALING; CRYSTALLIZATION; EV RANGE 01-10; GRAIN GROWTH; LASER RADIATION; LAYERS; MELTING; MELTING POINTS; NUCLEATION; SEMICONDUCTOR MATERIALS; SILICON ALLOYS; SOLIDIFICATION; TEMPERATURE DEPENDENCE; TEMPERATURE RANGE 0400-1000 K; THIN FILMS

Citation Formats

Her, Yung-Chiun, and Chen, Chih-Wei. Crystallization kinetics of ultrathin amorphous Si film induced by Al metal layer under thermal annealing and pulsed laser irradiation. United States: N. p., 2007. Web. doi:10.1063/1.2654512.
Her, Yung-Chiun, & Chen, Chih-Wei. Crystallization kinetics of ultrathin amorphous Si film induced by Al metal layer under thermal annealing and pulsed laser irradiation. United States. doi:10.1063/1.2654512.
Her, Yung-Chiun, and Chen, Chih-Wei. Thu . "Crystallization kinetics of ultrathin amorphous Si film induced by Al metal layer under thermal annealing and pulsed laser irradiation". United States. doi:10.1063/1.2654512.
@article{osti_20982702,
title = {Crystallization kinetics of ultrathin amorphous Si film induced by Al metal layer under thermal annealing and pulsed laser irradiation},
author = {Her, Yung-Chiun and Chen, Chih-Wei},
abstractNote = {The crystallization kinetics of ultrathin a-Si induced by Al under thermal annealing and pulsed laser irradiation has been studied. Under thermal annealing, the crystallization temperature and activation energy for crystallization of a-Si with a thin Al metal layer was reduced to around 340 degree sign C and 3.3 eV, respectively. The reaction exponent was determined to vary from 1.5 to 1.8, corresponding to a crystallization process in which grain growth occurs with nucleation, and the nucleation rate decreases with the progress of grain growth. Under high power pulsed laser irradiation, the crystallization and reamorphization of a-Si were found to take place sequentially in a-Si/Al. The reamorphization of a-Si in contact with a thin Al metal layer can be attributed to the melting of a-Si/Al initiated at the interface, due to the low melting temperature of Si-Al alloy and the rapid solidification that followed. Considering only the crystallization process, the activation energy for crystallization of a-Si induced by Al, estimated to be about 0.22 eV, was nearly an order of magnitude lower than that under thermal annealing. This may be explained by the explosive crystallization of a-Si by mechanical impact with a high power pulsed laser. In the meantime, the reaction exponent, determined to range from 1.9 to 2.2, was slightly higher than that under thermal annealing, indicating that the decrease of nucleation rate with the progress of grain growth during crystallization was slower, and the crystallization process became more nucleation dominant.},
doi = {10.1063/1.2654512},
journal = {Journal of Applied Physics},
number = 4,
volume = 101,
place = {United States},
year = {Thu Feb 15 00:00:00 EST 2007},
month = {Thu Feb 15 00:00:00 EST 2007}
}
  • Under thermal annealing, the crystallization temperatures of a-Si in a-Si/Cu and a-Si/Al bilayer recording films were significantly reduced to around 485 and 357 deg. C, respectively, and the activation energies for crystallization were reduced to about 3.3 eV. The formation of Cu{sub 3}Si phase prior to crystallization of a-Si was found to occur at around 175 deg. C in a-Si/Cu, while no Al silicide was observed in a-Si/Al before crystallization of a-Si. The reaction exponents for a-Si/Cu and a-Si/Al were determined to be around 1.8 and 1.6, respectively, corresponding to a crystallization process in which grain growth occurs with nucleation,more » and the nucleation rate decreases with the progress of grain growth. Under pulsed laser irradiation, the precipitation of Cu{sub 3}Si phases and crystallization of a-Si were observed in a-Si/Cu, while the crystallization and reamorphization of a-Si took place sequentially in a-Si/Al. The reaction exponents for a-Si/Cu and a-Si/Al, determined to be about 2.0 and 2.2, respectively, are slightly higher than those under thermal annealing, indicating that the crystallization processes of a-Si/Cu and a-Si/Al under pulsed laser irradiation are similar to those under thermal annealing. However, the decrease of nucleation rate with the progress of grain growth is slower. At the same time, the activation energies for crystallization of a-Si/Cu and a-Si/Al, estimated to be about 0.18 and 0.22 eV, respectively, are nearly an order of magnitude lower than those under thermal annealing. This may be explained by the explosive crystallization of a-Si by mechanical impact, with a high power pulsed laser.« less
  • The crystallization kinetics of a-Ge thin film induced by a thin Ni layer under thermal annealing and pulsed laser irradiation has been studied. Under thermal annealing, the crystallization temperature and activation energy for crystallization of a-Ge in the a-Ge/Ni bilayer recording film were significantly reduced to 385 deg. C and 2.4 eV, respectively, due to the fast Ge diffusion in the already formed germanide phases. The reaction exponent m of approx1.7 for the a-Ge/Ni bilayer corresponds to a crystallization process in which grain growth occurs with nucleation and the nucleation rate decreases with the progress of the grain growth process.more » Under pulsed laser irradiation, the maximum data-transfer rates of 22, 56, 74, and 112 Mbits/s can be achieved in the write-once blue-ray disk at the recording powers of 3, 4, 5, and 6 mW, respectively.« less
  • The crystallization kinetics of Cu/a-Si bilayer recording film under thermal and pulsed laser annealing has been studied. Under thermal annealing, the crystallization temperature and activation energy for crystallization of a-Si with a thin Cu metal layer were reduced to about 485 deg. C and 3.3{+-}0.1 eV, respectively. The reaction exponent was determined to be around 1.8, corresponding to a crystallization process in which grain growth occurs with nucleation, and the nucleation rate decreases with the progress of the grain growth process. Under pulsed laser annealing, the activation energy for crystallization of a-Si was estimated to be about 0.22 eV whichmore » is significantly lower than that under thermal annealing and may be explained by the explosive crystallization of a-Si, while the reaction exponent was found to vary from 1.2 to 1.4, corresponding to a grain-growth-controlled process associated with instantaneous nucleation.« less
  • Similar phase formation and crystallization behaviors have been observed in the a-Ge/Cu bilayer under thermal annealing and pulsed laser irradiation. The Cu{sub 3}Ge phase would form prior to the crystallization of a-Ge. The crystallization temperature and activation energy for crystallization of a-Ge were reduced to 310 deg. C and 2.75 eV, respectively, due to the fast Ge diffusion in the already formed germanide phases. The reaction exponent m of {approx}2.0 for the a-Ge/Cu bilayer corresponds to a crystallization process in which grain growth occurs with nucleation, and the nucleation rate decreases with the progress of the grain growth process. Undermore » pulsed laser irradiation, the maximum data-transfer-rates of 44, 56, 74, and 112 Mbit/s can be achieved in the write-once blue-ray disk at the recording powers of 3, 4, 5, and 6 mW, respectively. The a-Ge/Cu bilayer also demonstrated sufficient optical contrast and adequate absorptance for low power and high speed write-once blue-ray recording.« less
  • Though Ge crystallization has been widely studied, few works investigate metal-induced crystallization of ultrathin Ge films. For 2 nm Ge films in oxide matrix, crystallization becomes challenging due to easy oxidation and low mobility of Ge atoms. Introducing metal atoms may alleviate these problems, but the functions and the behaviours of metal atoms need to be clarified. This paper investigates the crystallization dynamics of a multilayer structure 1.9 nm Ge/0.5 nm Al/1.5 nm Al{sub 2}O{sub 3} under rapid thermal annealing (RTA). The functions of metal atoms, like effective anti-oxidation, downshifting Raman peaks, and incapability to decrease crystallization temperature, are found and explained. The metalmore » behaviours, such as inter-diffusion and defect generation, are supported with direct evidences, Al-Ge nanobicrystals, and Al cluster in Ge atoms. With these understandings, a two-step RTA process achieves high-quality 2 nm nanocrystal Ge films with Raman peak at 298 cm{sup −1} of FWHM 10.3 cm{sup −1} and atomic smooth interfaces.« less