TY - JOUR
T1 - Studies on Li3AlF6 thin film deposition utilizing conversion reactions of thin films
AU - Mäntymäki, Miia
AU - Mizohata, Kenichiro
AU - Heikkilä, Mikko J.
AU - Räisänen, Jyrki
AU - Ritala, Mikko
AU - Leskelä, Markku
PY - 2017/8/31
Y1 - 2017/8/31
N2 - The ternary lithium aluminum fluoride Li3AlF6 is formed from two optically interesting fluorides, LiF and AlF3. It has been reported to have a large electronic bandgap with a reasonable lithium-ion conductivity at room temperature, making it a potential electrolyte material for solid state lithium-ion batteries. Because of complications during attempts at direct atomic layer deposition of Li3AlF6, we have studied the deposition of the material using two conversion processes. In Process 1, a conversion reaction takes place when (Althd)3 (thd = 2,2,6,6-tetramethyl-3,5-heptanedionate) and TiF4 are sequentially pulsed onto LiF films. The Li3AlF6 films contained LiF as an impurity phase, as determined with grazing incidence X-ray diffraction (GIXRD), and a large amount of titanium impurity, as determined with time-of-flight elastic recoil detection analysis (ToF-ERDA). In Process 2, AlF3 films are exposed to Lithd vapor, resulting in a conversion reaction that produced Li3AlF6 with some LiF. These films have also been studied with GIXRD and ToF-ERDA, and contained much smaller amounts of titanium and other impurities. The Li:Al metal ratios vary depending on the extent of Lithd exposure. Field emission scanning electron microscopy (FESEM) revealed that the Li3AlF6 films are quite porous.
AB - The ternary lithium aluminum fluoride Li3AlF6 is formed from two optically interesting fluorides, LiF and AlF3. It has been reported to have a large electronic bandgap with a reasonable lithium-ion conductivity at room temperature, making it a potential electrolyte material for solid state lithium-ion batteries. Because of complications during attempts at direct atomic layer deposition of Li3AlF6, we have studied the deposition of the material using two conversion processes. In Process 1, a conversion reaction takes place when (Althd)3 (thd = 2,2,6,6-tetramethyl-3,5-heptanedionate) and TiF4 are sequentially pulsed onto LiF films. The Li3AlF6 films contained LiF as an impurity phase, as determined with grazing incidence X-ray diffraction (GIXRD), and a large amount of titanium impurity, as determined with time-of-flight elastic recoil detection analysis (ToF-ERDA). In Process 2, AlF3 films are exposed to Lithd vapor, resulting in a conversion reaction that produced Li3AlF6 with some LiF. These films have also been studied with GIXRD and ToF-ERDA, and contained much smaller amounts of titanium and other impurities. The Li:Al metal ratios vary depending on the extent of Lithd exposure. Field emission scanning electron microscopy (FESEM) revealed that the Li3AlF6 films are quite porous.
KW - Conversion reaction
KW - Fluoride thin films
KW - Lithium aluminum fluoride
KW - Thin films
UR - http://www.scopus.com/inward/record.url?scp=85019883930&partnerID=8YFLogxK
U2 - 10.1016/j.tsf.2017.05.026
DO - 10.1016/j.tsf.2017.05.026
M3 - Article
AN - SCOPUS:85019883930
VL - 636
SP - 26
EP - 33
JO - Thin Solid Films
JF - Thin Solid Films
SN - 0040-6090
ER -