Transferable Ga₂O₃ Membrane for Vertical and Flexible Electronics via One-Step Exfoliation

Abstract

Transferable Ga2O3 thin film membrane is desirable for vertical and flexible solar-blind photonics and high-power electronics applications. However, Ga2O3 epitaxially grown on rigid substrates such as sapphire, Si, and SiC hinders its exfoliation due to the strong covalent bond between Ga2O3 and substrates, determining its lateral device configuration and also hardly reaching the ever-increasing demand for wearable and foldable applications. Mica substrate, which has an atomic-level flat surface and high-temperature tolerance, could be a good candidate for the van der Waals (vdW) epitaxy of crystalline Ga2O3 membrane. Beyond that, benefiting from the weak vdW bond between Ga2O3 and mica substrate, in this work, the Ga2O3 membrane is exfoliated and transferred to arbitrary flexible and adhesive tape, allowing for the vertical and flexible electronic configuration. This straightforward exfoliation method is verified to be consistent and reproducible by the transfer and characterization of thick (∼380 nm)/thin (∼95 nm) κ-phase Ga2O3 and conductive n-type β-Ga2O3. Vertical photodetectors are fabricated based on the exfoliated Ga2O3 membrane, denoting the peak response at ∼250 nm. Through the integration of Ti/Au Ohmic contact and Ni/Ag Schottky contact electrode, the vertical photodetector exhibits self-powered photodetection behavior with a responsivity of 17 mA/W under zero bias. The vdW-bond-assisted exfoliation of the Ga2O3 membrane demonstrated here could provide enormous opportunities in the pursuit of vertical and flexible Ga2O3 electronics.

An enhanced ultrasensitive solar-blind UV photodetector based on an asymmetric Schottky junction designed with graphene/β-Ga2O3/Ag

“…It is evident that our detector displays excellent performance compared to other Ga 2 O 3 detectors that utilize graphene as the transparent electrode. 9,11,20,[24][25][26][46][47][48][49][50][51][52][53][54][55][56][57]…”

Applications of remote epitaxy and van der Waals epitaxy

“…Optical image of flexible solar-blind photodetectors using β-Ga 2 O 3 epilayer [ 34 ], d . UV light on/off cyclic tests of flexible Ga 2 O 3 photodetector [ 81 ], e . I-V ds characteristics of WS 2 epilayer-based photodetector according to V gs [ 82 ], f .…”

“…Oxide nanomembranes have been also considered as promising materials for achieving 3D hetero-integrated optoelectronic systems. The oxide thin-films were grown by the vdW epitaxy, and transferred to flexible substrates for demonstrating the practical optoelectronic applications [ 34 , 81 ]. A flexible solar-blind photodetector was realized by using a large-scale β-Ga 2 O 3 film which was grown by the vdW epitaxy on a compressive-strained epitaxial graphene as shown in Fig.…”

“…The flexible device displayed excellent photosensitivity of 151.1 A/W at a wavelength of 250 nm due to the wide band gap (~ 4.9 eV) of the β-Ga 2 O 3 nanomembrane. The vdW epitaxy of β-Ga 2 O 3 thin-film could be applied to the mica substrate as well as the structure of 2D material/mother substrate because the mica wafer had a stacked structure of 2D-like thin framework layers [ 81 ]. The β-Ga 2 O 3 thin-film grown on the mica was easily exfoliated by mechanical stress from a metal/adhesive tape-structured film, which could be accomplished by intentional destruction of weak vdW bindings between the mica layers.…”

Effect of high-temperature remelting on the properties of Sn-doped β-Ga2O3 crystal grown using the EFG method

“…[1][2][3][4][5][6] β-Ga 2 O 3 wide-band-gap semiconductor material is one of the fastest-developing semiconductor materials in the field of power electronics. [7][8][9][10] Compared with GaN, SiC, and other third-generation semiconductor materials, β-Ga 2 O 3 possesses superior material properties. Ga 2 O 3 has a wider band gap width (∼4.9 eV), high breakdown field strength (∼8 MV cm −1 ), and higher Baliga's figure-of-merit (BFOM, ∼3444).…”