Chi-Chung Ling

The University of Hong Kong | HKU · Department of Physics

Undoped and Ga-doped ZnO films were grown on c-sapphire using pulsed laser deposition (PLD) at the substrate temperature of 600 °C. Positron annihilation spectroscopy study (PAS) shows that the dominant VZn-related defect in the as-grown undoped ZnO grown with relative low oxygen pressure P(O2) is a vacancy cluster (most likely a VZn-nVO complex wi...

High dielectric constant materials are of particular current interests as indispensable components in transistors, capacitors, etc. In this context, there are emerging trends to exploit defect engineering in dielectric ceramics for enhancing the performance. However, demonstrations of similar high dielectric performance in integration-compatible cr...

Oxide dielectrics, such as HfO2, Al2O3, etc, are widely used to improve the performance of two-dimensional (2D) semiconductors in electronic devices. However, future low-power electronic devices need higher dielectric constant (κ) to reduce the leakage current, and these super-high-κ materials are challenging to produce on wafer-scale. Here, we rep...

Junction barrier Schottky diode fabrication involves multi-folded Al ion implantation for realizing p-type doping. With a new fabrication recipe, we demonstrate that the trade-off between sufficiently high Al acceptor activation and sufficiently low residual concentration of carbon vacancies - acting as free carrier traps - may be resolved applying...

For the potential applications in ferroelectric switching and piezoelectric nano-generator device, the promising ferroelectric properties of two dimensional (2D) layered In2Se3 attracted much attention. In the present study, 2D In2Se3 flakes down to monolayers are grown by chemical vapor deposition (CVD) technique on mica substrate with the structu...

Recently, the optoelectronic memory is capturing growing attention due to its integrated function of sense and memory as well as multilevel storage ability. Although tens of states have been reported in literature, there are still three obvious deficiencies in most of the optoelectronic memories: large programming voltage (>20 V), high optical powe...

Magnetite (Fe3O4) nanoparticles have been considered as a promising microwave absorption materials. To further tune their electromagnetic interference shielding efficiency, different compositions of doped Ni0.01-xZnxFe2.99O4 (x = 0.0, 0.005, 0.01) nanoparticles were synthesized by the co-precipitation technique. The prepared nanoparticles structure...

O-polar and Zn-polar ZnO films were fabricated by pulsed laser deposition. The Zn-polar sample has a lower electron concentration and higher electron mobility compared with the O-polar sample. This is due to the lower abundance of hydrogen which acts as shallow donor in the Zn-polar film. A Coincidence Doppler broadening study showed that VZn-2VO i...

Recently, halide perovskite materials have shown great potential in photodetection for their large light absorption coefficient and long carrier diffusion length. In contrast to the reported sandwich-structured devices and single-junction...

High-Dielectric Transparent Films A new example of high-k materials exploration is provided, demonstrating a remarkable breakthrough. Specifically, in article number 2107168, Dong Huang, Chi-Chung Ling, and co-workers adapt the acceptor-donor co-doping method in enhancing dielectric performance. The dielectric constant reaches ≈200 and the optical...

High‐κ Gate Dielectrics In article number 2200580, Jing Yu, Wei Han, Francis Chi‐Chung Ling, and co‐workers prepare large‐size (Ga, Cu) co‐doped ZnO films with super‐high dielectric constant (κ > 50) and good homogeneity by a pulsed laser deposition (PLD) method. The performance of SnS2 field‐effect transistor reveals that high‐κ Al2O3/GCZO gate di...

Ion implantation is an excellent method to introduce defects into semiconductors, extending their functionalities in a controllable way. Herein, we investigated an option to use crystallographically aligned implants as an additional route to control the balance between optically active defects, selecting ZnO as a test material. The optical data wer...

Er-doped ZnO (Zn(1-x)Er(x)O) films with (002) preferential orientated wurtzite structure were fabricated on a c-plane sapphire substrate by pulsed laser deposition (PLD). The effects of Er composition, oxygen pressure during growth, and post-growth annealing on the films' structural, electrical, and optical properties were studied by employing a co...

In the progress of nonlinear optics, multiphoton absorption (MPA) upconversion lasing enables many vital applications in bioimaging, three-dimensional optical data storage, and photodynamic therapy. Here, efficient four-photon absorption upconversion lasing from the ZnO/ZnMgO multiple quantum wells (MQWs) at room temperature is realized. Moreover,...

Pulsed laser deposition is employed to fabricate as-grown amorphous and post-growth annealed crystalline β-Ga 2 O 3 films. The films annealed at temperatures above 600 °C are found to exhibit a pure monolithic phase with a bandgap of 4.7 eV. The thermally activated donor ionization and dielectric relaxation of these films are systematically investi...

Discovering multifunctional materials is of paramount importance for advancing the science and technology. Herein, we report on an optical phenomenon modulated by an electrical process that happened at the metal-ZnO:Cu junction, for which the light emission intensity from the photoluminescence is tuned reversibly by applying electric bias to the ju...

Dielectric thin films having high permittivity (high-k) and low dielectric loss is essential for developing high performance capacitive devices like metal oxide field effect transistor or thin film transistor. Ga ion implantation performed on Cu-doped ZnO film fabricated by pulsed laser deposition with optimized doping concentrations and post-impla...

Aqueous Zinc ion batteries grant intriguing potential to large-scale energy storage, but they are still plagued by trade-off in high discharge capacity and long cycle life. In this work, such a critical barrier can be well solved by a novel cathode, rare-earth lanthanum orthovanadate (LaVO4). For traditional aqueous cells, the LaVO4 (LVO) cathode d...

Rechargeable aqueous zinc-ion batteries (ZIBs) are promising candidates in energy storage because of intrinsic safety, low-cost and eco-friendliness. However, restricted by cathode materials, ZIBs usually exhibit inferior capacity and limited cycling performance. Herein, an efficient dual-phase strategy is employed to fabricate novel heterogeneous...

The fabrication of ohmic contacts on wide bandgap semiconductors, such as β-Ga2O3, is difficult as the scarcity of metals with low-enough work function. The insertion of n⁺-doped metal oxide layer between metal and the β-Ga2O3 layers are effective for improving the ohmic behaviour. β-Ga2O3, Erbium doped ZnO (ErZO), and Gallium doped ZnO (GZO) films...

Hetero-MoO3/MoO2@N-doped carbon nanobelt anodes (h-MoO3/MoO2@NC) with long lifespan and superior rate capability were proposed by a simple in situ reduction tactic, in which pristine MoO3 was transformed into heterogeneous MoO3/MoO2. The hetero-MoO3/MoO2 architecture significantly improves the electronic conductivity and affords abundant oxygen def...

The performance of quasi-2D perovskite light emitting diodes (LEDs) with mixed small cations, cesium and formamidinium (FA), is significantly affected by their ratio. The best devices obtained for Cs:FA ratio of 1:1 exhibit a maximum external quantum efficiency (EQE) of 12.1%, maximum luminance of 15 070 cd m⁻² and maximum current efficiency of 46....

Controlling the carbon vacancy (VC) in silicon carbide (SiC) is one of the major remaining bottleneck in manufacturing of high voltage SiC bipolar devices, because VC provokes recombination levels in the bandgap, offensively reducing the charge carrier lifetime. In literature, prominent VC evolutions have been measured by capacitance spectroscopy em...

Aiming to enhance the dielectric constant and maintaining a relatively low dielectric loss, transparent acceptor-donor (Cu-Ga) co-doped ZnO films were fabricated on c-sapphire using pulsed laser deposition. With Ga=0.5 wt% and Cu=8 wt%, the dielectric constant was optimised while the dielectric loss is relatively low ( 204 and 0.27 respectively at...

Indium selenide (In2Se3) has got much recent attraction in a variety of research areas mainly due to its multiphase structure. Many existing studies, however, have focused on growth of α and β phase, while chemical vapor deposition (CVD) growth of the γ-phase has only been achieved for micon-thick flakes with the assistance of iodine trichloride (I...

Using first-principle calculations, the magnetic properties of the monovacancies and the Sb-related defects including VZn, VO, SbZn, SbO, SbZn-VZn and SbZn-2VZn are studied. It is found that the isolated VZn with the charge state of 0 and -1 can contribute to ferromagnetism in ZnO material. The substitution of Sb on O sites (SbO⁰) also results in m...

The mesh-like hard carbon loaded SbPO4 (SbPO4/NTC) was harvested and employed as anode material for sodium ion batteries. Profiting from prominent capacitance, porous structure, and sufficient buffering space, the composite realizes high electrochemical kinetics for sodium ion storage. The SbPO4/NTC composite gains impressive battery properties, su...

Herein, layer-structured β-In 2 Se 3 microwires were proposed by a facile chemical vapour deposition (CVD) method without any catalyst. As a novel kind of building blocks for constructing photodetectors, these one dimensional...

The biological waste of mangosteen epicarp was recycled to fabricate biomass carbon; then, a biowaste-sustained MoSe2/biowaste carbon/carbon nanotubes composite (MoSe2/BC/CNTs) was constructed via a hydrothermal process. As a high-efficiency anode material for sodium ion batteries (SIBs) and potassium ion batteries (PIBs), the MoSe2/BC/CNTs composi...

O-polar and Zn-polar ZnO films were grown on c-sapphire by pulsed laser deposition. Positron annihilation spectroscopy study reveals that the VZn-related defects in the ZnO films with different polarities are different in structure and their thermal evolution is different. Hall effect measurement and luminescence spectroscopy reveal that the electr...

The origin of room temperature ferromagnetism in undoped ZnO is still a question of debate. Experimental and theoretical findings are inconclusive as to the predominant contributor for the magnetic behavior of undoped ZnO. First principle calculation pseudopotential method was used to systematically determine the relaxed atomic geometry, the format...

Anionic defect (oxygen vacancies)-enriched ZnMn2O4 nanorods (OZMO) were manufactured through a facile coprecipitation/chemical reduction route. The synergetic mechanism of rich oxygen vacancies, abundant mesopores, and prominent pseudocapacitance endows the OZMO nanorods with long-term chemical durability for high-efficient lithium/sodium storage....

Systematic Raman spectroscopic study was conducted on the wurtzite (002) Sb-doped ZnO films grown by pulsed laser deposition with different Sb doping levels and annealed at different temperatures, with the undoped, Cu-doped and Ga-doped ZnO films for comparison. Three additional Raman modes 235 cm⁻¹, 510 cm⁻¹ and 534 cm⁻¹ were observed only in the...

Undoped ZnO films grown on sapphire by pulsed laser deposition are magnetic at room temperature. A comprehensive study involving x-ray diffraction, positron annihilation spectroscopy, and superconducting quantum Interference device-vibrating sample magnetometer is performed to study the origin of the observed magnetization. Correlations between the...

Transition metal oxides have a wide potential application for high‐performance energy storage devices. In this research, hierarchically rambutan‐like Zn3V3O8 hollow spheres are fabricated by using a simple reflux/anneal strategy. These hollow spheres are enriched with highly porous feature and favourable surface area, which can afford abundant Li+/...

The presence of defects in thermoelectric materials plays a significant role in the modification their properties by influencing the behavior of electrons and phonons. Dopants with a unique f‐orbital can directly cause distortions in electronic density of states (eDOS) and phonon transport mechanism by intentionally inducing defects in their lattic...

In the past few years, silane coupling agents are often used to modify the surface of silicon materials; however, researches in preparation of SiOX-based materials pyrolyzed from silane coupling agents are seldom reported. Hence, in order to prepare amorphous SiOX@C anodes for Li-ion storage, we adopted three kinds of silane coupling agents as orga...

Through systematic optimization studies of Li and Al co-doped ZnO ceramics we demonstrate that colossal permittivity with low dielectric loss (εr = 9862 and tan δ = 0.159 at the frequency of 1 kHz) at room temperature can be achieved in Zn0.99(Li0.1, Al0.2)0.033O. The colossal dielectric constant (CDC) and low dielectric loss in this ceramic have r...

Rechargeable aqueous Zn‐ion batteries (ZIBs) show attractive potential in energy storage devices on account of high safety and eco‐friendliness. Yet the lack of suitable cathode materials prevented the practical application of ZIBs. In our work, a Na0.56V2O5 (NVO) nanobelt cathode material has been fabricated via a hydrothermal reaction. The prepar...

Rare earth element-Erbium (Er) doped ZnO (ErZO) thin films were deposited on glass substrates by pulsed laser deposition (PLD). The effect of the Er doping concentration on photoelectric properties of ErZO thin films was investigated in the range of 0–2.0 wt. %. The Er doping resulted in the improvement of n-type conductivity as compared with intri...

The research of functional materials has attracted extensive attention in recent years, and its advancement nitrifies the developments of modern sciences and technologies like green sciences and energy, aerospace, medical and health, telecommunications, and information technology. The present book aims to summarize the research activities carried o...

Lamellar V5O12·6H2O nanobelts coupled with inert Zn(OH)2·0.5H2O were in‐situ fabricated via a facile hydrothermal strategy. Herein, the inert Zn(OH)2·0.5H2O phase can act as a buffer matrix to strengthen the structural stability of V5O12·6H2O host material, relieving the severe volume variation. Therefore, benefiting from large interplanar spacing...

As a novel sodium ion battery anode material, 3D pollen-scaffolded NiSe composite encapsulated by metal-organic framework-derived (MOF-derived) carbon shell is synthesized, denoted as P–[email protected] The results depict that well-crystallized NiSe particles were in-situ grown on 3D pollen framework, preventing the particles aggregation effective...

Low‐cost, non‐toxic, and abundant red phosphorus (RP) with high gravimetric discharge/charge capacity has been recognized as a promising anode candidate for potassium‐ion batteries (KIBs). However, the massive volumetric change, severe agglomeration, and rapid capacity attenuation during discharge/charge cycles are major obstacles for their practic...

Plant oil–inspired 3D flower‐like Zn3V3O8 nanospheres coupled with nitrogen doped (N‐doped) carbon synthesized via the microemulsion/calcination strategy are used as anodes for lithium‐/sodium‐ion batteries (LIBs/SIBs). The synergistic interaction between the unique 3D flower‐like structure and the existence of N‐doped carbon can provide enough spa...

1D porous ZnCo2O4 cuboids tailored by green natural soybean oil (SZCO) were harvested by a facile micro-emulsion strategy and were used as anodes for lithium ion batteries (LIBs). The as-prepared ZnCo2O4 particles in a length range of 20–50 μm are characterized by 1D porous cuboid architecture and large specific surface area, exhibiting a high init...

A novel porous nano‑silicon/[email protected] anode with superior cycling stability and long-term durability has been proposed by the facile strategy of mechanical ball-milling/low-temperature calcination. This porous architecture can contain enough void spaces to stabilize the severe volume expansion, and provide sufficient migration channels for...

Currently, there are three primary obstacles to the development of high-performance supercapacitors: low electron conductivity of the electrode materials used, their poor ion-transport efficiency, and the unstable structure. Herein, to overcome these obstacles, one-dimensional Zn2GeO4 (ZGO) rods were grown within a carbon nanotube (CNT) framework u...

Novel nano-structured films of V2O5 are prepared by pulsed laser deposition method. Nanoscaled V2O5 ridges lie on SrTiO3 substrate and construct into grid-textured structures. Structural properties of the films have been analyzed by scanning electron microscope, X-ray diffraction and transmission electron microscope. The films have enlarged surface...

Multiple quantum wells (MQWs) have enabled a myriad of technological applications; however, their optical emission is currently severely constrained by the presence of undesirable defects, which limit their performance in advanced photonic devices. Here we present a new route to achieve highly luminescent oxide-based MQWs by rapid remote plasma ann...

We demonstrate a simple and inexpensive method of surface polarity control of ZnO grown by pulsed laser deposition (PLD). The polarity control is achieved in a straightforward way by changing the thickness of MgO buffer layer. The Zn- and O-polar ZnO films possess very distinct growth rate, electron concentration and mobility as well as different d...

The 1D bundle-like NiCo2O4@TiO2 hybrid was synthesized by a general and effective microemulsion strategy. It is found that after cycles the primitive 1D shape has been translated into broccoli-like fashion accompanied with abundant pores, enough active sites and convenient diffusion path, which endows the hybrid with high lithium storage capability...

High-quality γ-In2Se3 thin films and a γ-In2Se3/p-Si heterojunction were prepared using pulse laser deposition (PLD). The band offset of this heterojunction was studied by XPS and the band structure was found to be type II structure. The valence band offset (ΔEv) and the conduction band offset (ΔEc) of the heterojunction were determined to be 1.2 ±...

An unique 3D mesoporous interconnected Ni12P5/CNTs hybrid was constructed by a facile one‐step hydrothermal method and investigated as anodes toward lithium ion batteries. The results show that Ni12P5 nanoparticles are well hinged by the flexible CNTs, forming a hierarchically integrated structure. It delivers an initial discharge capacity of 1108...

A unique flexible configuration with ordered porous rice ball-like ZnCo2O4 (ZCO) microspheres embedded in reduced graphene oxide (rGO) network was demonstrated by a facile solvothermal route and vacuum filtration method. As binder-free anodes for LIBs, sandwiched structure ZCO/rGO electrode synergistically realized high lithium storage capability a...

Systematic magnetic, electronic, and electrical studies on the Cu0.04Zn0.96O/Ga0.01Zn0.99O cell structure grown on (001) sapphire by the pulsed laser deposition technique show that the Cu multivalent (CuM+) ions modulate magnetic and resistive states of the cells. The magnetic moment is found to be reduced by ∼30% during the high resistance state (...

Sb-doped ZnO films were fabricated on c-plane sapphire using the pulsed laser deposition method and characterized by the Hall effect measurement, X-ray photoelectron spectroscopy, X-ray diffraction, photoluminescence and positron annihilation spectroscopy. Systematic studies on the growth conditions with different Sb composition, oxygen pressure an...

Er-doped ZnO films were grown on c-plane sapphire by employing the pulsed laser deposition method. In accordance with the previously reported literature studies, post-growth annealing was required to activate the optical emission originated from the intra-shell transitions of the Er atoms. Importantly, the present systematic studies revealed that t...