Epitaxial growth of a β-Ga2O3 (−201)-oriented thin film on a threefold symmetrical SrTiO3 (111) substrate for heterogeneous integration

Abstract

Epitaxial growth of a wide bandgap semiconductor β-Ga2O3 thin film with high crystal quality plays a decisive role in constructing optical and electronic devices. However, except for the native substrate, the scarcity of appropriate non-native substrates or the poor crystallization of the deposit in thin film growth severely limits the fabrication and applicability of the final heterostructures and devices. Here, by taking the consistent symmetry and closely matched atomic spacing between β-Ga2O3 (−201) and the cubic perovskite (111)-oriented plane of SrTiO3, we realize the epitaxial growth of single crystal β-Ga2O3 (−201) thin films on the SrTiO3 (111) substrate by the pulsed laser deposition method, as confirmed by wide-range reciprocal-space mapping and high-resolution scanning transmission electron microscopy. The fabricated β-Ga2O3 (−201) photodetector device on the SrTiO3 (111) substrate exhibits excellent ultraviolet optical detection performance with large on/off switching ratios and a fast response speed. Moreover, the β-Ga2O3/SrTiO3 (111) heterojunction shows type-II heterostructure characteristics for energy band alignment, which displays superior ability for electron–hole pairs separation with large conduction and small valance band offsets of 1.68 and 0.09 eV, respectively. The results offer us a new way to obtain high-quality β-Ga2O3 (−201) thin film heterostructures on cubic SrTiO3 (111) substrates and fabricate β-Ga2O3-based optical and electronic devices.

Freestanding Crystalline β-Ga2O3 Flexible Membrane Obtained via Lattice Epitaxy Engineering for High-Performance Optoelectronic Device

“…Moreover, with the close atom spacing in the β-Ga 2 O 3 (−201) plane, LSMO (111) plane, and the SrTiO 3 (111) plane, the compressive strain is about 6%, which is comparable with that of Ga 2 O 3 grown on an Al 2 O 3 (0001) substrate, further verifying the feasibility of coherent epitaxial growth. 22 Therefore, based on the suitable lattice structure and atomic arrangement, if LSMO could act as a sacrificial layer, then a freestanding crystalline β-Ga 2 O 3 membrane might be obtainable.…”

“…From the schematic diagram of the cross-sectional β-Ga 2 O 3 /LSMO/SrTiO 3 heterostructure (Figure b), the SrO 3 4– (LaO 3 3– ) anion plane of LSMO (111) matches well with both the O 2– anion plane of β-Ga 2 O 3 (−201) and the SrO 3 4– plane of SrTiO 3 (111). Moreover, with the close atom spacing in the β-Ga 2 O 3 (−201) plane, LSMO (111) plane, and the SrTiO 3 (111) plane, the compressive strain is about 6%, which is comparable with that of Ga 2 O 3 grown on an Al 2 O 3 (0001) substrate, further verifying the feasibility of coherent epitaxial growth . Therefore, based on the suitable lattice structure and atomic arrangement, if LSMO could act as a sacrificial layer, then a freestanding crystalline β-Ga 2 O 3 membrane might be obtainable.…”

“…Previously, we have successfully realized the growth of a crystalline β-Ga 2 O 3 film on a 3-fold symmetrical SrTiO 3 (111)-terminated substrate, and the small lattice mismatch between the film and the substrate guarantees the high quality of the β-Ga 2 O 3 film . It is also well-known that many materials, such as La 0.7 Sr 0.3 MnO 3 (LSMO), can be epitaxially grown on SrTiO 3 . , Inspired by this fact, we proposed that through lattice symmetry engineering a high-quality crystalline Ga 2 O 3 /LSMO/SrTiO 3 heterostructure can be available.…”

Ultrasensitive Self-Powered Flexible Crystalline β-Ga2O3-Based Photodetector Obtained through Lattice Symmetry and Band Alignment Engineering

“…Recently, due to its high ultraviolet light absorption efficiency and stable physical and chemical properties, the wide band gap semiconductor material β-Ga 2 O 3 has gradually drawn much attention for various ultraviolet applications, especially for deep ultraviolet PDs. − With the development of wearable electronics, flexible self-powered β-Ga 2 O 3 -based PDs are becoming a research focus for the Ga 2 O 3 scientific and industrial communities. However, until now, due to the limitation of growth conditions, most flexible self-powered photodetectors are based on amorphous or poorly crystalline β-Ga 2 O 3 materials. − It is well-known that the sample quality and its interfacial energy band alignment, especially the crystallinity of semiconductor junction, plays a significant role to the device performance .…”