| 1. |
- Deng, Liying, et al.
(author)
-
Can fluorophlogopite mica be used as an alkali metal ion source to boost the growth of two-dimensional molybdenum dioxide?
- 2023
-
In: Applied Surface Science. - : Elsevier BV. - 0169-4332. ; 612
-
Journal article (peer-reviewed)abstract
- Everyone familiar with two-dimensional (2D) materials is aware of fluorophlogopite mica (FM), which has an atomic-level flat surface that provides an ideal platform for the growth of 2D materials. Since it has been demonstrated that the alkali metal ions (AMI) can aid in the growth of large-sized 2D materials by chemical vapor deposition (CVD) in recent years, it became a major mystery whether FM which contains AMI benefits from them in the preparation of 2D materials by CVD, too. In this article, we dispelled this ambiguity and discovered that temperature is the key for FM as an AMI source to boost the growth of large-sized 2D materials. We carried out variable temperature experiments and found that FM can indeed be incorporated into the growth of large-sized 2D materials as an AMI source at high temperatures and successfully obtained the highly crystalline MoO2 with a larger size compared to those without FM. This finding is of great importance to the understanding of the growth mechanism of FM for 2D materials by CVD and to better exploit its role in the growth of 2D materials.
|
|
| 2. |
- Deng, Liying, et al.
(author)
-
KCl acts as a flux to assist the growth of sub-millimeter-scale metallic 2D non-layered molybdenum dioxide
- 2024
-
In: Rare Metals. - 1001-0521 .- 1867-7185. ; In Press
-
Journal article (peer-reviewed)abstract
- Two-dimensional (2D) metal oxides (2DMOs), such as MoO2, have made impressive strides in recent years, and their applicability in a number of fields such as electronic devices, optoelectronic devices and lasers has been demonstrated. However, 2DMOs present challenges in their synthesis using conventional methods due to their non-van der Waals nature. We report that KCl acts as a flux to prepare large-area 2DMOs with sub-millimeter scale. We systematically investigate the effects of temperature, homogeneous time and cooling rate on the products in the flux method, demonstrating that in this reaction a saturated homogenous solution is obtained upon the melting of the salt and precursor. Afterward, the cooling rate was adjusted to regulate the thickness of the target crystals, leading to the precipitation of 2D non-layered material from the supersaturated solution; by applying this method, the highly crystalline non-layered 2D MoO2 flakes with so far the largest lateral size of up to sub-millimeter scale (~ 464 μm) were yielded. Electrical studies have revealed that the 2D MoO2 features metallic properties, with an excellent sheet resistance as low as 99 Ω·square−1 at room temperature, and exhibits a property of charge density wave in the measurement of resistivity as a function of temperature. Graphical abstract: TOC (Table of Content) (Figure presented.)
|
|
| 3. |
- Pan, Kui, et al.
(author)
-
Highly effective transfer of micro-LED pixels to the intermediate and rigid substrate with weak and tunable adhesion by thiol modification
- 2023
-
In: Nanoscale. - : Royal Society of Chemistry (RSC). - 2040-3372 .- 2040-3364. ; 15:9, s. 4420-4428
-
Journal article (peer-reviewed)abstract
- Based on transfer printing technology, micro-LED pixels can be transferred to different types and sizes of driving substrates to realize displays with different application scenarios. To achieve a successful transfer, GaN-based micro-LEDs first need to be separated from the original epitaxial substrate. Here, micro-LED pixels (each size 25 μm × 30 μm) on the sapphire substrate were transferred to a flexible semiconductor wafer processing (SWP) tape that is strongly sticky by conventional laser lift-off (LLO) techniques. The pixels on the SWP tape were then transferred by using a sacrificial layer of non-crosslinked oligomeric polystyrene (PS) film onto the intermediate and rigid substrate (IRS) with weak and tunable adhesion by thiol (-SH) modification. The electrode of the micro-LED is Au metal, which forms Au-S bonds with the surface of the IRS to fix the pixels. The rigid substrate helps ensure that the pixel spacing is almost unchanged during the stamp transfer process, and the weak and tunable adhesion facilitates the pixels being picked up by the stamp. The experimental results demonstrate that the pixels can be efficiently transferred to the IRS by LLO and sacrificial layer-assistance, which will provide the possibility of achieving the further transfer of pixels to different types and sizes of driving substrates by a suitable transfer stamp. The transfer process details are discussed, which can provide insights into the transfer of micro-nano devices through polymer sacrificial layers.
|
|
| 4. |
- Pan, Kui, et al.
(author)
-
Monolithically and Vertically Integrated LED-on-FET Device Based on a Novel GaN Epitaxial Structure
- 2023
-
In: IEEE Transactions on Electron Devices. - 1557-9646 .- 0018-9383. ; 70:12, s. 6393-6398
-
Journal article (peer-reviewed)abstract
- Optoelectronic devices, such as light-emitting diodes (LEDs), based on GaN-based semiconductor compounds are widely used for their advantages of long life, high reliability, and low energy consumption. The persistent challenge is integrating LED with transistors to achieve smaller size, lighter weight, higher speed, and more reliable optoelectronic integrated circuits. Here, we report monolithically and vertically integrated LED-on-FET devices fabricated on a novel GaN epitaxial structure. The designed device structure and fabrication process are simple. It also eliminates the extra area occupied by the transistor, and the shared n-GaN layer between the LED and FET reduces interconnect resistance and improves reliability. The measured threshold voltage (V-Th) of the LED-on-FET device is extrapolated as 3.9 V at the voltage (V-DD) of 5 V, and V-Th decreases with the increase of V-DD . More importantly, the gate voltage (V-GS) shows good performance in modulated electroluminescence (EL) intensity and switching capability of the LED. The integrated LED efficiently emits light modulation with a wavelength of 440 nm at V-DD= 9 V and V-GS=4-9 V (step = 1 V), which are necessary for devices in applications, such as displays and smart lighting. This epitaxy structure and integration scheme is promising in achieving large-scale optoelectronic integrated circuits, such as the next-generation micro-LED and nano-LED with super compact integrated drivers.
|
|
| 5. |
- Sun, Xiaoming, et al.
(author)
-
Adjustable hardness of hydrogel for promoting vascularization and maintaining sternness of stem cells in skin flap regeneration
- 2018
-
In: Applied Materials Today. - : Elsevier. - 2352-9407. ; 13, s. 54-63
-
Journal article (peer-reviewed)abstract
- The matrix mechanical stiffness of biomaterials plays an important role in the pluripotency and biological function of stem cells in the microenvironment. It is a key step to adjust the stiffness of biomaterials for inducing stem cells to promote vascularization in order to promote damaged tissue repair. In this study, we transplant adipose derived stem cells (ADSCs) within an in situ forming dextran hydrogel with controllable mechanical strength formed by cross-linking glycidyl methacrylate derivatized dextran and dithiothreitol, which can regulate the stemness and biological functions of stem cells. We show that softer dextran hydrogel can better maintain stemness markers expression of ADSCs, and significantly stimulate ADSCs to secrete angiogenic factors. The ADSCs-encapsulated hydrogel distinctly promote the skin flap survival compared to direct cell injection. Bioluminescence imaging analysis shows that in situ forming dextran hydrogel can improve cells retention, and postmortem analysis reveals that the transplanted ADSCs with hydrogel can promote vascularization. These results support the use of injectable dextran hydrogel for skin ischemia tissue regeneration. (C) 2018 Elsevier Ltd. All rights reserved.
|
|
| 6. |
- Tian, Liang, et al.
(author)
-
Electroless Deposition of 4 μm High Ni/Au Bumps for 8 μm Pitch Interconnection
- 2022
-
In: ACS Applied Electronic Materials. - : American Chemical Society (ACS). - 2637-6113. ; 4:10, s. 4966-4971
-
Journal article (peer-reviewed)abstract
- We propose that electroless plating is a superb approach to preparing metallic bumps with an ultrafine pitch for the integration of a micro light-emitting diode (micro-LED). Electroless plating does not suffer from lift-off-related issues, which are ubiquitous in thermal evaporation. Besides, it can result in much more uniform bumps than electroplating because the bump height is not affected by the current distribution. This study reports ultrafine pitch Ni/Au bumps fabricated by electroless nickel immersion gold (ENIG) plating. Furthermore, cheap metals iron and nickel are selected to catalyze the electroless nickel process. The results indicate that uniform and consistent Ni/Au bumps can be obtained through the iron sheet and nickel layer method. Besides, no voids and impurities are found inside the bumps, which is beneficial for the following interconnection process. Moreover, the change in Ni bump height values with the electroless plating time is also provided.
|
|
| 7. |
- Zhu, Xuanyu, et al.
(author)
-
Liquid Phase Deposition of Hafnium Oxide Thin Films
- 2024
-
In: IEEE Transactions on Dielectrics and Electrical Insulation. - 1558-4135 .- 1070-9878. ; 31:4, s. 1659-1665
-
Journal article (peer-reviewed)abstract
- Hafnium oxide (HfO2) thin films were successfully prepared by the liquid phase deposition (LPD) method. The surface appearance, composition, optical characteristics, and electrical properties of HfO2 thin films generated by LPD were studied, as well as the reaction mechanism. The results reveal that the chemical composition of HfO2 thin films generated by LPD is pure and the structure is dense and continuous. The physical and chemical properties are stable, and the film thickness is around 40 nm after sufficient growth. The transmittance of HfO2 films after annealing at 500 °C is greater than 93%, the leakage current density at 1 V is 1.38× 10-6 A/cm2, and the breakdown voltage is 6.4 V. At the same time, based on the capacitance value at 1 MHz, the dielectric constant of the HfO2 film is estimated to be around 20.4.
|
|
