TY - JOUR
T1 - Thin Films of α-Quartz GeO2 on TiO2-Buffered Quartz Substrates
AU - Zhou, Silang
AU - de Hond, Kit
AU - Antoja-Lleonart, Jordi
AU - Ocelík, Václav
AU - Koster, Gertjan
AU - Rijnders, Guus
AU - Noheda, Beatriz
N1 - Publisher Copyright:
© 2023 The Authors. Published by American Chemical Society.
PY - 2024/1/3
Y1 - 2024/1/3
N2 - α-Quartz (SiO2) is one of the most widely used piezoelectric materials. However, the challenges associated with the control of the crystallization and the growth process limit its production to the hydrothermal growth of bulk crystals. GeO2 can also crystallize into the α-quartz phase, with a higher piezoelectric response and better thermal stability than SiO2. In a previous study, we have found that GeO2 crystallization on nonquartz substrates shows a tendency to form spherulites with a randomized orientation; while epitaxial growth of crystalline GeO2 thin films can take place on quartz (SiO2) substrates. However, in the latter case, the α-β phase transition that takes place in both substrates and thin films during heating deteriorates the long-range order and, thus, the piezoelectric properties. Here, we report the ousting of spherulitic growth by using a buffer layer. Using TiO2 as a buffer layer, the epitaxial strain of the substrates can be transferred to the growing films, leading to the oriented crystallization of GeO2 in the α-quartz phase. Moreover, since the TiO2 separates the substrates and the thin films, the thermal stability of the GeO2 is kept across the substrate’s phase transitions. Our findings reveal the complexity of the crystallization process of quartz thin films and present a way to eliminate the tendency for spherulitic growth of quartz thin films by epitaxial strain.
AB - α-Quartz (SiO2) is one of the most widely used piezoelectric materials. However, the challenges associated with the control of the crystallization and the growth process limit its production to the hydrothermal growth of bulk crystals. GeO2 can also crystallize into the α-quartz phase, with a higher piezoelectric response and better thermal stability than SiO2. In a previous study, we have found that GeO2 crystallization on nonquartz substrates shows a tendency to form spherulites with a randomized orientation; while epitaxial growth of crystalline GeO2 thin films can take place on quartz (SiO2) substrates. However, in the latter case, the α-β phase transition that takes place in both substrates and thin films during heating deteriorates the long-range order and, thus, the piezoelectric properties. Here, we report the ousting of spherulitic growth by using a buffer layer. Using TiO2 as a buffer layer, the epitaxial strain of the substrates can be transferred to the growing films, leading to the oriented crystallization of GeO2 in the α-quartz phase. Moreover, since the TiO2 separates the substrates and the thin films, the thermal stability of the GeO2 is kept across the substrate’s phase transitions. Our findings reveal the complexity of the crystallization process of quartz thin films and present a way to eliminate the tendency for spherulitic growth of quartz thin films by epitaxial strain.
UR - http://www.scopus.com/inward/record.url?scp=85180952568&partnerID=8YFLogxK
U2 - 10.1021/acs.cgd.3c00476
DO - 10.1021/acs.cgd.3c00476
M3 - Article
AN - SCOPUS:85180952568
SN - 1528-7483
VL - 24
SP - 71
EP - 78
JO - Crystal Growth and Design
JF - Crystal Growth and Design
IS - 1
ER -