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Theβ-Ga₂O₃nanomembrane (NM)/diamond heterostructure is one of the promising ultra-wide bandgap heterostructures that offers numerous complementary advantages from both materials. In this work, we have investigated the thermal properties of theβ-Ga₂O₃NM/diamond heterostructure with three different thicknesses ofβ-Ga₂O₃nanomembranes (NMs), namely 100 nm, 1000 nm, and 4000 nm thickβ-Ga₂O₃NMs using Raman thermometry. The thermal property—temperature relationships of theseβ-Ga₂O₃NM/diamond heterostructures, such as thermal conductivity and interfacial thermal boundary conductance were determined under different temperature conditions (from 100 K to 500 K with a 40 K interval). The result provides benchmark knowledge about the thermal conductivity ofβ-Ga₂O₃NMs over a wide temperature range for the design of novelβ-Ga₂O₃-based power electronics and optoelectronics.

 

This paper reports the fabrication of β-Ga 2 O 3 nanomembrane (NM) based flexible photodetectors (PDs) and the investigation of their optoelectrical properties under bending conditions. Flexible β-Ga 2 O 3 NM PDs exhibited reliable solar-blind photo-detection under bending conditions. Interestingly, a slight shifting in wavelength of the maximum solar-blind photo-current was observed under the bending condition. To investigate the reason for this peak shifting, the optical properties of β-Ga 2 O 3 NMs under different strain conditions were measured, which revealed changes in the refractive index, extinction coefficient and bandgap of strained β-Ga 2 O 3 NMs due to the presence of nano-sized cracks in the β-Ga 2 O 3 NMs. The results of a multiphysics simulation and a density-functional theory calculation for strained β-Ga 2 O 3 NMs showed that the conduction band minimum and the valence band maximum states were shifted nearly linearly with the applied uniaxial strain, which caused changes in the optical properties of the β-Ga 2 O 3 NM. We also found that nano-gaps in the β-Ga 2 O 3 NM play a crucial role in enhancing the photoresponsivity of the β-Ga 2 O 3 NM PD under bending conditions due to the secondary light absorption caused by reflected light from the nano-gap surfaces. Therefore, this research provides a viable route to realize high-performance flexible photodetectors, which are one of the indispensable components in future flexible sensor systems. 

A free‐standing β‐Ga₂O₃, also called β‐Ga₂O₃nanomembrane (NM), is an important next‐generation wide bandgap semiconductor that can be used for myriad high‐performance future flexible electronics. However, details of structure‐property relationships of β‐Ga₂O₃NM under strain conditions have not yet investigated. In this paper, the electrical properties of β‐Ga₂O₃NM under different uniaxial strain conditions using various surface analysis methods are systematically investigated and layer‐delamination and fractures are revealed. The electrical characterization shows that the presence of nanometer‐sized gaps between fractured pieces in β‐Ga₂O₃NM causes a severe property degradation due to higher resistance and uneven charge distribution in β‐Ga₂O₃NM which is also confirmed by the multiphysics simulation. Interestingly, the degraded performance in β‐Ga₂O₃NM is substantially recovered by introducing excessive OH‐bonds in fractured β‐Ga₂O₃NM via the water vapor treatment. The X‐ray photoelectron spectroscopy study reveals that a formation of OH‐bonds by the water vapor treatment chemically connects nano‐gaps. Thus, the treated β‐Ga₂O₃samples exhibit reliable and stable recovered electrical properties up to ≈90% of their initial values. Therefore, this result offers a viable route for utilizing β‐Ga₂O₃NMs as a next‐generation material for a myriad of high‐performance flexible electronics and optoelectronic applications.

 

Here, high power flexible Schottky barrier diodes (SBDs) are demonstrated on a plastic substrate using single crystalline β‐Ga₂O₃nanomembranes (NMs). In order to realize flexible high power β‐Ga₂O₃SBDs, sub‐micron thick freestanding β‐Ga₂O₃NMs are created from a bulk β‐Ga₂O₃substrate and transfer‐printed onto the plastic substrate via a microtransfer printing method. It is revealed that the material property of β‐Ga₂O₃NMs such as crystal structure, electron affinity, and bandgap remains unchanged compared with its bulk properties. Flexible β‐Ga₂O₃SBDs exhibit the record high critical breakdown field strength (E_c) of 1.2 MV cm⁻¹in the flat condition and 1.07 MV cm⁻¹ofE_cunder the bending condition. Overall, flexible β‐Ga₂O₃SBDs offer great promise for future flexible energy convergence systems and are expected to provide a much larger and more versatile platform to address a broader range of high‐performance flexible applications.