Hala Aljawhari
@kau.edu.sa
Physics Department
King Abdulaziz University
Scopus Publications
Scopus Publications
Badriah Sultan, Qasem Drmosh, ElSayed Shalaan, and Hala Al-Jawhari
Elsevier BV
Laila J. AL-Rehaili, Reem M. Altuwirqi, Areej A. Aljarb, and Hala A. Al-Jawhari
Elsevier BV
Tianchao Guo, Xiangming Xu, Chen Liu, Yizhou Wang, Yongjiu Lei, Bin Fang, Lin Shi, Hang Liu, Mrinal K. Hota, Hala A. Al-Jawhari,et al.
American Chemical Society (ACS)
Direct MXene deposition on large-area 2D semiconductor surfaces can provide design versatility for the fabrication of MXene-based electronic devices (MXetronics). However, it is challenging to deposit highly uniform wafer-scale hydrophilic MXene films (e.g., Ti3C2Tx) on hydrophobic 2D semiconductor channel materials (e.g., MoS2). Here, we demonstrate a modified drop-casting (MDC) process for the deposition of MXene on MoS2 without any pretreatment, which typically degrades the quality of either MXene or MoS2. Different from the traditional drop-casting method, which usually forms rough and thick films at the micrometer scale, our MDC method can form an ultrathin Ti3C2Tx film (ca. 10 nm) based on a MXene-introduced MoS2 surface polarization phenomenon. In addition, our MDC process does not require any pretreatment, unlike MXene spray-coating that usually requires a hydrophilic pretreatment of the substrate surface before deposition. This process offers a significant advantage for Ti3C2Tx film deposition on UV-ozone- or O2-plasma-sensitive surfaces. Using the MDC process, we fabricated wafer-scale n-type Ti3C2Tx–MoS2 van der Waals heterojunction transistors, achieving an average effective electron mobility of ∼40 cm2·V–1·s–1, on/off current ratios exceeding 104, and subthreshold swings of under 200 mV·dec–1. The proposed MDC process can considerably enhance the applications of MXenes, especially the design of MXene/semiconductor nanoelectronics.
Asmaa Mudhaffar, Badriah Sultan, ElSayed Shalaan, and Hala Al-Jawhari
Springer Science and Business Media LLC
Roaa Sait, Hala Al-Jawhari, Aisha Ganash, Shofarul Wustoni, Long Chen, Mohamed Nejib Hedhili, Nimer Wehbe, Deema Hussein, Alazouf Alhowity, Saleh Baeesa,et al.
American Chemical Society (ACS)
The efficacy of neural electrode stimulation and recording hinges significantly on the choice of a neural electrode interface material. Transition metal carbides (TMCs), particularly titanium carbide (TiC), have demonstrated exceptional chemical stability and high electrical conductivity. Yet, the fabrication of TiC thin films and their potential application as neural electrode interfaces remains relatively unexplored. Herein, we present a systematic examination of TiC thin films synthesized through nonreactive radio frequency (RF) magnetron sputtering. TiC films were optimized toward high areal capacitance, low impedance, and stable electrochemical cyclability. We varied the RF power and deposition pressure to pinpoint the optimal properties, focusing on the deposition rate, surface roughness, crystallinity, and elemental composition to achieve high areal capacitance and low impedance. The best-performing TiC film showed an areal capacitance of 475 μF/cm2 with a capacitance retention of 93% after 5000 cycles. In addition, the electrochemical performance of the optimum film under varying scanning rates demonstrated a stable electrochemical performance even under dynamic and fast-changing stimulation conditions. Furthermore, the in vitro cell culture for 3 weeks revealed excellent biocompatibility, promoting cell growth compared with a control substrate. This work presents a novel contribution, highlighting the potential of sputtered TiC thin films as robust neural electrode interface materials.
Hala A. Al-Jawhari and Nuha A. Alhebshi
MDPI AG
In this work, we introduce an environmental and sustainable approach to grow free standing heterogeneous Cu2O-Cu(OH)2 nanocomposites on a Cu mesh using spinach leaf extract and glycerol. Structural characterizations for samples annealed at 200 °C revealed that there is more Cu(OH)2 than Cu2O on the mesh surface. The photocatalytic activity of the green synthesized catalyst was studied for degradation of a cationic dye methylene blue (MB), an anionic dye methyl orange (MO) and a mixture of both dyes. The effect of changing the dye’s initial pH value on the photodegradation process was explored. After 40 min of irradiation under sunlight, with a maximum intensity of 5 mW/cm2, a basic MB dye (pH-11) showed about 80% color removal with an average kinetic rate of 94.5 m·min−1. In contrast, 93% of the acidified MO dye (pH-2) was degraded with an average kinetic rate of 126.5 m·min−1. Moreover, the versatility of the Cu2O-Cu(OH)2@Cu mesh was evaluated using a remarkable selective separability for a mixture of MB and MO at pH = 2, in the dark and under normal sunlight. Such promising outcomes indicate the potential of our green composites to degrade dyes as both photocatalysts under daylight and as Fenton-like catalysts in darkness.
Ashwag Almaimouni, Arwa Kutbee, Asmaa Mudhaffar, and Hala Al-Jawhari
Springer Science and Business Media LLC
Hala A. Al‐Jawhari
Wiley
Hala Al-Jawhari, Hend Badahdah, Asmaa Mudhaffar, and Reem Altuwirqi
Springer Science and Business Media LLC
Hala Al-Jawhari, Hanan Bin-Thiyab, and Nihal Elbialy
Elsevier BV
Asmaa Mudhaffar and Hala Al-Jawhari
Trans Tech Publications, Ltd.
Strontium titanate SrTiO3 thin films have been fabricated by radio frequency magnetron sputtering on P-type Si at substrate temperature of 200°C. Two different postdeposition annealing methods were applied on the sputtered films. Specifically, conventional thermal annealing at 300°C for 60 min and photoactivation treatment under deep ultraviolet-ozone for 30 min. The dielectric properties of the SrTiO3 thin films were investigated by fabricating Au/STO/p-Si MOS capacitors. A dielectric constant (κ) with a value of 13 was obtained for as-deposited film, which has a thickness of 107 nm. While post-annealed samples showed elevated values of κ, precisely, 15.33 and 19.32 for films exposed to deep ultraviolet-ozone photoactivation and films annealed at 300°C, respectively. All devices showed a leakage current in the order of 10-8 A/cm2 at 1V. Based on XPS analysis, photo-activated films revealed the lowest percentage of oxygen vacancies, which designates the capability of this technique to enhancing films quality at a lower temperature.
Hend Badahdah, Arwa Kutbee, Dina Katowah, Mahmoud A. Hussein, Noorah Al-Ahmadi, Reem Altuwirqi, and Hala Al-Jawhari
Elsevier BV
Nuha Alhebshi, Hao Huang, Rokiya Ghandour, Nada K. Alghamdi, Ohoud Alharbi, Shahad Aljurban, Jr-Hau He, and Hala Al-Jawhari
Elsevier BV
Abstract Here we introduce an ecological facile method to grow heterogeneous copper oxide (CuxO) nanocomposites on a Cu mesh using spinach leaf extract. After annealing at different temperatures, morphological and structural characterizations revealed that samples annealed at 300 °C comprise the highest Cu+/Cu2+ ratio and reveal the most porous structure. Such samples exhibited dual catalytic functions as both photocatalysts for dye degradation, and electrocatalysts for hydrogen evolution. Their photocatalytic activity for degradation of methylene blue (MB) was investigated under sunlight irradiation of 7 mW/cm2. A complete degradation, with an average kinetic rate of 63.2 m min−1, was achieved after 60 min. Moreover, the samples revealed a good electrochemical catalytic property for hydrogen evolution reaction (HER) in acidic medium. They exhibited HER onset at 357 mV with a small charge transfer resistance of 8.2 Ω. Such promising outcomes could open a new path for mass-production applications in water-energy fields.
Reem M. Altuwirqi, Alaa S. Albakri, Hala Al-Jawhari, and Entesar A. Ganash
Elsevier BV
Abstract Copper (Cu) and copper oxide (CuxO) nanoparticles (NPs) were fabricated via a green method using Pulsed Laser Ablation in Liquid (PLAL) technique. The Q-switched Nd:YAG laser of wavelength 532 nm was focused on a solution containing pure copper powder mixed in spinach leaves extract. The effect of ablation time, ablation medium and laser irradiance on the propreties of the produced particles were investigated. Analytical methods were employed to characterize the produced particles such as X-Ray Diffraction (XRD) and Transmission Electron Microscopy (TEM). TEM images showed nearly spherical NPs with diameters from 1−12 nm depending on the laser parameters. Furthermore, the TEM images showed planes spacings related to Cu and CuxO NPs which were confirmed with the XRD analysis. The size of the produced NPs was affected by the irradiation time. The liquid medium did not have a great effect on the size of the fabricated NPs. However, using spinach extract supported the production of more CuxO NPs, in comparison to using distilled water. This investigation can provide guidance to a green synthesis technique for fabricating CuxO NPs using spinach leaves extract as an ablation medium.
Reem M. Altuwirqi, Bayan Baatiyah, Eman Nugali, Zeina Hashim, and Hala Al-Jawhari
Hindawi Limited
The second harmonic wavelength of a neodymium-doped yttrium-aluminum-garnet (Nd-YAG) laser (λ=532 nm) was used in a pulsed laser ablation technique (PLAL) to synthesize aluminum nanoparticles suspended in white vinegar from an aluminum target. The nanoparticles were characterized by HRTEM and UV-Vis spectrophotometry. They were found to range in size between 2 and 50 nm in diameter, with an average diameter of 12±9 nm. The nanoparticles had a maximum absorption peak at 237 nm and were found to exhibit a core-shell structure with an Al core coated by a thin layer of an amorphous material which could be attributed to amorphous carbon. HRTEM results revealed that the small nanoparticles (<20 nm) had an fcc phase of aluminum crystalline structure, where the larger particles represented alumina (γ-Al2O3) nanoparticles. Such observation suggests that the use of white vinegar as an ablation medium could facilitate the synthesis of aluminum nanoparticles with minimal evidence of the existence of aluminum oxide nanoparticles in the resultant suspension.
Zhenwei Wang, Fwzah H. Alshammari, Hesham Omran, Mrinal K. Hota, Hala A. Al‐Jawhari, Khaled N. Salama, and Husam N. Alshareef
Wiley
Hala Al-Jawhari, Roaa Al-Murashi, Lujin Abu Saba, Nuha Alhebshi, and Reem Altuwirqi
Elsevier BV
Abstract In this work, we report a green, nontoxic, no-residue method for degradation of methylene blue (MB) using Cu-Cu2O films prepared with spinach leaves extract. The photocatalytic activity for two composite films with different copper concentrations, specifically 0.01 M and 0.05 M, was investigated under natural outdoor light which has an average irradiation of 3 mW/cm2. An overall degradation of 97.7% was achieved using the 0.05 M Cu-Cu2O composite, over a time duration of 180 min. We believe that the native oxidizing property of spinach extract played a major role in enhancing the photocatalytic activities of our films and gave them equitable reaction kinetics under natural daylight.
Fwzah H. Alshammari, Mrinal K. Hota, Zhenwei Wang, Hala Al-jawhari, and Husam N. Alshareef
Wiley
Atomic-layer-deposited SnO2 is used as a gate electrode to replace indium tin oxide (ITO) in thin-film transistors and circuits for the first time. The SnO2 films deposited at 200 °C show low electrical resistivity of ≈3.1 × 10−3 Ω cm with ≈93% transparency in most of the visible range of the electromagnetic spectrum. Thin-film transistors fabricated with SnO2 gates show excellent transistor properties including saturation mobility of 15.3 cm2 V−1 s−1, a low subthreshold swing of ≈130 mV dec−1, a high on/off ratio of ≈109, and an excellent electrical stability under constant-voltage stressing conditions to the gate terminal. Moreover, the SnO2-gated thin-film transistors show excellent electrical characteristics when used in electronic circuits such as negative channel metal oxide semiconductor (NMOS) inverters and ring oscillators. The NMOS inverters exhibit a low propagation stage delay of ≈150 ns with high DC voltage gain of ≈382. A high oscillation frequency of ≈303 kHz is obtained from the output sinusoidal signal of the 11-stage NMOS inverter-based ring oscillators. These results show that SnO2 can effectively replace ITO in transparent electronics and sensor applications.
Safeyah Al-Shehri, Norah Al-Senany, Reem Altuwirqi, Amani Bayahya, Fwzah Al-Shammari, Zhenwei Wang, and Hala Al-Jawhari
Elsevier BV
Abstract In this work, we employed two nontoxic green chemistry methods to develop solution-processed copper oxide Cu x O thin films at low annealing temperature of 200 °C. The first aqueous precursor of Cu x O was prepared by mixing the copper powder with spinach leaves extract, whereas the other solution was formulated using the water-based polyol reduction method of Cu(II) nitrate. The as-prepared precursors were then spun on SiO 2 /P + Si substrates to form nanoscale Metal-Oxide-Semiconductor (MOS) capacitors by which some valuable information about the Cu x O semiconductor films and their interfaces with dielectric were acquired. Both fabricated MOS capacitors exhibited p-type polarity with negative flat-band voltages. However, the MOS based on spinach extract-Cu x O films showed small hysteresis of 100 mV, which could be attributed to its large grain size that sequentially leads to smooth interface and less trap density.
Sarah Alsharif, Hanaa Farhan, and Hala Al-Jawhari
EDP Sciences
A 3D model for p -type Cu 2 O thin-film transistor (TFT) was simulated for the first time using COMSOL Multiphysics. The main objective of this modeling is to investigate the effect of patterning either the channel or the gate on the performance of Cu 2 O TFTs. Considering the ideal case, where traps and leakage current are not incorporated, we compared the performance of three different designs; unpatterned, patterned channel and patterned channel and gate TFTs. In each case, the transfer curve, output characteristics, current flow and potential distribution were clarified. The comparison between main parameters showed that the unpatterned model overestimated the field effect mobility µFE by 37.4% over the fully patterned TFT, nevertheless, the latter exhibited the highest on/off current ratio and the lowest off-current. A simulation of experimental output characteristics reported for Cu 2 O TFT was performed to check the model viability.
N.A. Al-Ahmadi and H.A. Al-Jawhari
Elsevier BV
Abstract The effect of epitaxial layer thickness on electrical characteristics of two Ti/n-Al0.33Ga0.67As Schottky barrier diodes was studied in the temperature range of 300–420 K. Comparing the current–voltage (I–V) characteristics of two samples with epitaxial layer thicknesses of 2 μm and 1.5 μm discloses that the device with a thinner epitaxial layer has a higher barrier height and hence a lower reverse current. Specifically, we found that increasing the Al0.33Ga0.67As thickness from 1.5 μm to 2 μm would lower the value of the barrier height by ∼12% at 300 K. We associated such retrogression of the electrical quality to the presence of deep level traps in the Si:AlxGa1−xAs layer. For both samples we found that the effective barrier height decreases with increasing the annealing temperature. Yet, the sample with a thinner layer showed more stability and less temperature dependence.
H.A. Al-Jawhari
Elsevier BV
One of the crucial challenges that face the wide-spread implementation of flexible and transparent electronics is the lack of high performance p-type semiconductor material. Cu2O in thin-film form is a potentially attractive material for such applications because of its native p-type semi-conductivity, transparency, abundant availability, non-toxic nature, and low production cost. This review summarizes recent research on using copper oxide Cu2O thin films to produce p-type transparent thin-film transistors (TFTs) and complementary metal–oxide–semiconductor (CMOS) devices. After a short introduction about the main advantages of Cu2O semiconductor material, different methods for depositing and growing Cu2O thin films are discussed. The hi-tech development, along with the associated obstacles, of the Cu2O-based thin-film transistors is reviewed, with special emphasis on those made of sputtered Cu2O films. Finally, the bilayer scheme as one of the most exciting and promising technique for both TFTs and CMOS devices will be considered.
Zhenwei Wang, Hala A. Al-Jawhari, Pradipta K. Nayak, J. A. Caraveo-Frescas, Nini Wei, M. N. Hedhili, and H. N. Alshareef
Springer Science and Business Media LLC
In this report, both p- and n-type tin oxide thin-film transistors (TFTs) were simultaneously achieved using single-step deposition of the tin oxide channel layer. The tuning of charge carrier polarity in the tin oxide channel is achieved by selectively depositing a copper oxide capping layer on top of tin oxide, which serves as an oxygen source, providing additional oxygen to form an n-type tin dioxide phase. The oxidation process can be realized by annealing at temperature as low as 190°C in air, which is significantly lower than the temperature generally required to form tin dioxide. Based on this approach, CMOS inverters based entirely on tin oxide TFTs were fabricated. Our method provides a solution to lower the process temperature for tin dioxide phase, which facilitates the application of this transparent oxide semiconductor in emerging electronic devices field.
H. A. Al-Jawhari, J. A. Caraveo-Frescas, and M. N. Hedhili
Springer Science and Business Media LLC
The effect of copper oxide layer thickness on the performance of Cu2O/SnO bilayer thin-film transistors was investigated. By using sputtered Cu2O films produced at an oxygen partial pressure, Opp, of 10% as the upper layer and 3% Opp SnO films as the lower layer we built a matrix of bottom-gate Cu2O/SnO bilayer thin-film transistors of different thickness. We found that the thickness of the Cu2O layer is of major importance in oxidation of the SnO layer underneath. The thicker the Cu2O layer, the more the underlying SnO layer is oxidized, and, hence, the more transistor mobility is enhanced at a specific temperature. Both device performance and the annealing temperature required could be adjusted by controlling the thickness of each layer of Cu2O/SnO bilayer thin-film transistors.