In this paper, we demonstrate microwave flexible thin-film transistors (TFTs) on biodegradable substrates towards potential green portable devices. The combination of cellulose nanofibrillated fiber (CNF) substrate, which is a biobased and biodegradable platform, with transferrable single crystalline Si nanomembrane (Si NM), enables the realization of truly biodegradable, flexible, and high performance devices. Double-gate flexible Si NM TFTs built on a CNF substrate have shown an electron mobility of 160 cm2/V·s and fT and fmax of 4.9 GHz and 10.6 GHz, respectively. This demonstration proves the microwave frequency capability and, considering today's wide spread use of wireless devices, thus indicates the much wider utility of CNF substrates than that has been demonstrated before. The demonstration may also pave the way toward portable green devices that would generate less persistent waste and save more valuable resources.
A much-simplified method of making flexible GaN blue light-emitting diode (LED) array on a plastic substrate was demonstrated. A sticky elastomeric stamp was first brought into contact with prefabricated GaN LED array on a sapphire substrate. Laser liftoff was applied by shining laser light through the sapphire substrate. The released LED array sitting on the stamp was transferred to a polyethylene terephthalate substrate that was coated with an adhesive layer to finish the fabrication process. Careful investigation of the built-in stress in the GaN LED layer using Raman spectroscopy revealed that the maximum stress that allows for intact GaN LED layer release and transfer was 0.7 GPa. The method drastically simplifies the cumbersome conventional GaN layer transferring method while preserving the original layout of the GaN LED array. Due to its simple and practical characteristics, the method is expected to greatly facilitate the development of versatile transferrable GaN LED applications on various substrates at a much-reduced cost.
In this paper, the authors report resonant cavity (RC) metal-semiconductor-metal (MSM) germanium nanomembrane (Ge NM) photodetectors via transfer printing. The dislocation-free Ge NM layer was transferred onto an ultrathin Si NM/SiO2 distributed Bragg reflector. As a result, a low dark current density of 1 × 10−9 A/μm2 and a quantum efficiency of 17.3% at 1.55 μm, which is twice larger than the quantum efficiency without a bottom mirror, were measured from the transferred RC MSM Ge photodetector. The enhancement of the quantum efficiency is verified by simulation.
In this paper, we report ultra-thin distributed Bragg reflectors (DBRs) via stacked single-crystal silicon (Si) nanomembranes (NMs). Mesh hole-free single-crystal Si NMs were released from a Si-on-insulator substrate and transferred to quartz and Si substrates. Thermal oxidation was applied to the transferred Si NM to form high-quality SiO2 and thus a Si/SiO2 pair with uniform and precisely controlled thicknesses. The Si/SiO2 layers, as smooth as epitaxial grown layers, minimize scattering loss at the interface and in between the layers. As a result, a reflection of 99.8% at the wavelength range from 1350 nm to 1650 nm can be measured from a 2.5-pair DBR on a quartz substrate and 3-pair DBR on a Si substrate with thickness of 0.87 μm and 1.14 μm, respectively. The high reflection, ultra-thin DBRs developed here, which can be applied to almost any devices and materials, holds potential for application in high performance optoelectronic devices and photonics applications.
A distributed Bragg reflector (DBR) consisting of a single-crystal Si nanomembrane (NM) layer formed by the transfer printing technique on top of an evaporated amorphous Si (a-Si)/SiO2 DBR structure was demonstrated. The reflectivity of different DBR structures/pairs is measured and verified it by the simulation. An improved surface roughness of the top layer by employing a Si NM suggests that the smoother single crystalline surface not only minimizes light scattering loss but also can be an epitaxial template layer for subsequent Si growth without contributing any strain. The results indicate a simple pathway toward achieving high performance Si/SiO2 DBRs employing Si NM as a top layer. This method could also lead to the fabrication of large-area, high performance NM based DBRs at low cost with high throughput.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.