In this paper, we demonstrated large-size free-standing single-crystal β-Ga 2 O 3 NMs fabricated by the hydrogen implantation and lift-off process directly from MOCVD grown β-Ga 2 O 3 epifilms on native substrates. The optimum implantation conditions were simulated with a Monte-Carlo simulation method to obtain a high hydrogen concentration with a narrow ion distribution at the desired depth. Two as grown β-Ga 2 O 3 samples with different orientations ([100] and [001]) were used to successfully create 1.2 μm thick β-Ga 2 O 3 NMs without any physical damage. These β-Ga 2 O 3 NMs were then transfer-printed onto rigid and flexible substrates such as SiC and polyimide substrates. Various material characterization studies were performed to investigate their crystal quality, surface morphologies, optical properties, mechanical properties, and bandgaps before and after the lift-off and revealed that the good material quality was maintained. This result offers several benefits in that the thickness, doping, and size of β-Ga 2 O 3 NMs can be fully controlled. Moreover, more advanced β-Ga 2 O 3 -based NM structures such as (Al x Ga 1−x ) 2 O 3 /Ga 2 O 3 heterostructure NMs can be directly created from their bulk epitaxy substrates;more »
Flexible crystalline β-Ga 2 O 3 solar-blind photodetectors
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 more »
- Award ID(s):
- 1809077
- Publication Date:
- NSF-PAR ID:
- 10284027
- Journal Name:
- Journal of Materials Chemistry C
- Volume:
- 8
- Issue:
- 42
- Page Range or eLocation-ID:
- 14732 to 14739
- ISSN:
- 2050-7526
- Sponsoring Org:
- National Science Foundation
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- Publisher's Version of Record
- https://doi.org/10.1039/D0TC03740K
