Improvement of Ga_(2)O_(3)vertical Schottky barrier diode by constructing NiO/Ga_(2)O_(3)heterojunction

The high critical electric field strength of Ga_(2)O_(3)enables higher operating voltages and reduced switching losses in power electronic devices.Suitable Schottky metals and epitaxial films are essential for further enhancing device performance.In this work,the fabrication of vertical Ga_(2)O_(3)barrier diodes with three different barrier metals was carried out on an n--Ga_(2)O_(3)homogeneous epitaxial film deposited on an n+-β-Ga_(2)O_(3)substrate by metal-organic chemical vapor deposition,excluding the use of edge terminals.The ideal factor,barrier height,specific on-resistance,and breakdown voltage characteristics of all devices were investigated at room temperature.In addition,the vertical Ga_(2)O_(3)barrier diodes achieve a higher breakdown volt-age and exhibit a reverse leakage as low as 4.82×10^(-8)A/cm^(2)by constructing a NiO/Ga_(2)O_(3)heterojunction.Therefore,Ga_(2)O_(3)power detailed investigations into Schottky barrier metal and NiO/Ga_(2)O_(3)heterojunction of Ga_(2)O_(3)homogeneous epitaxial films are of great research potential in high-efficiency,high-power,and high-reliability applications.

Assessing high-energy x-ray and proton irradiation effects on electrical properties of P-GaN and N-GaN thin films

The effects of ionizing and displacement irradiation of high-energy x-ray and 2-MeV proton on GaN thin films were investigated and compared in this study.The electrical properties of both P-GaN and N-GaN,separated from power devices,were gauged for fundamental analysis.It was found that the electrical properties of P-GaN were improved as a consequence of the disruption of the Mg-H bond induced by high-dose x-ray irradiation,as indicated by the Hall and circular transmission line model.Specifically,under a 100-Mrad(Si)x-ray dose,the specific contact resistance pc of P-GaN decreased by 30%,and the hole carrier concentration increased significantly.Additionally,the atom displacement damage effect of a 2-MeV proton of 1×10^(13)p/cm^(2)led to a significant degradation of the electrical properties of P-GaN,while those of N-GaN remained unchanged.P-GaN was found to be more sensitive to irradiation than N-GaN thin film.The effectiveness of x-ray irradiation in enhancing the electrical properties of P-GaN thin films was demonstrated in this study.

Construction of PEG-mediated Genetic Transformation and Gene Knockout System in Fusarium oxysporum f. sp.cubense Tropic Race 4

Fusarium wilt of banana, caused by Fusarium oxysporum f. sp. cubense tropic race 4(Foc TR4), is a typical vascular and soil-borne disease which has significantly threatened the sustainable development of banana industry. In order to reveal the infection process and pathogenesis of Foc TR4, the young mycelia(66.7 mg/ml) of wild-type strain of Foc TR4(WT-Foc TR4) cultured for 18-20 h were lysed with enzyme mixture for protoplast formation, which consisted of 25 mg/ml driselase, 0.4 mg/ml chitinase, 15 mg/ml lysing enzyme and 1.2 mol/L potassium chloride. The resulted protoplasts of 2×10~7 cells/ml were used to test the efficiency of transformation mediated by polyethylene glycol, and up to 9 transformants per microgram of DNA were obtained. AmCyan, RFP and YFP genes were stably transferred into the WT-Foc TR4, separately, using the protoplast transformation system. The gene FoOCH1 encoding α-1, 6-mannosyltransferase in the WT-Foc TR4 was knocked out using the split-marker recombination technology. The genetic transformation and gene knockout system in this pathogen lays a foundation for the study of functional genomics and plant-pathogen interactions.

A low temperature processable tin oxide interlayer via aminemodification for efficient and stable organic solar cells

The exploitation of proper electron transport layers(ETLs)and interface optimization can play a pivotal role to promote the performance of organic solar cells(OSCs).In this work,low temperature processable tin oxide(SnO_(2))colloidal nanoparticles with ethanolamine(EA)treatment are successfully employed for efficient and stable OSCs with light soaking free.The EA is chemically bonded with SnO_(2),and the ethanolamine treated tin oxide(E-SnO_(2))layer delivers a suitable work function of 4.10 eV and a unique surface texture with suspended polar moieties.The enhanced performance of E-SnO_(2) based OSCs can be attributed to the improved charge transport and electron extraction,which is correlated with the regulated energy level alignment and contact quality of E-SnO_(2)/active layer.As a result,considerable power conversion efficiencies(PCEs)of 10.30%,13.93%and 15.38%for PTB7-Th/PC_(71) BM,PM7/ITC6-4 F and PM6/Y6 based OSCs have been realized with E-SnO_(2) as ETL,respectively.Compared with ZnO based devices,the E-SnO_(2) based OSCs exhibit an improved light aging stability,which can retain 94.3%of their initial PCE of 15.38%after 100 h light aging for E-SnO_(2)/PM6/Y6 based OSCs.This work demonstrates that the enormous potential of E-SnO_(2) to serve as ETL for high-efficiency and stable OSCs.

Study on SGDC Electrolyte Film Prepared by RF Magnetron Sputtering

Sm and Gd co-doped Ceria (SGDC:Sm_(0.1)Gd_(0.1)Ce_(0.8)O_(1.90)) films as the electrolytes were investigated for the IT-SOFCs (intermediate-temperature solid oxide fuel cells).SGDC sensing films were successfully prepared on the Al_2O_3 substrates by RF-magnetron sputtering.The relationship between sputtering parameters and film microstructure was discussed, and the optimum parameters were gained.The crystal structure analysis and surface morphologic observation of the SGDC films were carried out through X-ray diffraction (XRD) and scanning electron microscopy (SEM).The oxygen ion conductivity of the SGDC film was evaluated by AC impedance spectroscopy at the different temperatures.The XRD analysis shows that the SGDC films grow preferentially along the (111) compact plane.The crystallinity of the SGDC films is enhanced with the increase of the RF sputtering power from 150 W to 250 W.The oxygen ion conductivity of the SGDC was measured at the temperature from 600℃to 800℃in air by AC impedance spectroscopy.The result shows that a high oxygen ion conductivity of 2.44×10^(-2) S.cm^(-1) was achieved at 800℃.

Heating induced aggregation in non-fullerene organic solar cells towards high performance

Molecular ordering within the photoactive layer plays a crucial role in determining the device performance of organic solar cells(OSCs).However,the simultaneous molecular ordering processes of polymer donors and non-fullerene acceptors(NFAs)during solution casting usually bring confinement effect,leading to insufficient structural order of photovoltaic components.Herein,the molecular packing of mINPOIC NFA is effectively formed through a heating induced aggregation strategy,with the aggregation of PBDB-T,which has a strong temperature dependence,is retarded by casting on a preheated substrate to reduce its interference toward m-INPOIC.A sequent thermal annealing treatment is then applied to promote the ordering of PBDB-T and achieve balanced aggregation of both donors and acceptors,resulting in the achievement of a maximum efficiency of 13.9% of PBDB-T:m-INPOIC binary OSCs.This work disentangles the interactions of donor polymer and NFA during the solution casting process and develops a rational strategy to enhance the molecular packing of NFAs to boost device performance.

Regulating the morphology of fluorinated non-fullerene acceptor and polymer donor via binary solvent mixture for high efficiency polymer solar cells

Fluorinated non-fullerene acceptors(NFAs) usually have planar backbone and a higher tendency to crystallize compared to their non-fluorinated counterparts, which leads to enhanced charge mobility in organic solar cells(OSCs). However, this selforganization behavior may result in excessive phase separation with electron donors and thereby deteriorate device efficiency.Herein, we demonstrate an effective approach to tune the molecular organization of a fluorinated NFA(INPIC-4 F), and its phase separation with the donor PBDB-T, by varying the casting solvent. A prolonged film drying time encourages the crystallization of INPIC-4 F into spherulites and consequently results in excessive phase separation, leading to a low device power conversion efficiency(PCE) of 8.1%. Contrarily, a drying time leads to fine mixed domains with inefficient charge transport properties,resulting in a moderate device PCE of 11.4%. An intermediate film drying time results in the formation of face-on π-π stacked PBDB-T and INPIC-4 F domains with continuous phase-separated networks, which facilitates light absorption, exciton dissociation as well as balanced charge transport towards the electrode, and achieves a remarkable PCE of 13.1%. This work provides a rational guide for optimizing the molecular ordering of NFAs and electron donors for high device efficiency.

Design Rules of the Mixing Phase and Impacts on Device Performance in High-Efficiency Organic Photovoltaics

In nonfullerene acceptor-(NFA-)based solar cells,the exciton splitting takes place at both domain interface and donor/acceptor mixture,which brings in the state of mixing phase into focus.The energetics and morphology are key parameters dictating the charge generation,diffusion,and recombination.It is revealed that tailoringthe electronic properties of the mixing region by doping with larger-bandgap components could reduce the density of state but elevate the filling state level,leading to improved open-circuit voltage(V_(OC))and reduced recombination.The monomolecular and bimolecular recombinations are shown to be intercorrelated,which show a Gaussian-like relationship with V_(OC) and linear relationship with short-circuit current density(JSC)and fill factor(FF).The kinetics of hole transfer and exciton diffusion scale with JSC similarly,indicating the carrier generation in mixing region and crystalline domain are equally important.From the morphology perspective,the crystalline order could contribute to V_(OC) improvement,and the fibrillar structure strongly affects the FF.These observations highlight the importance of the mixing region and its connection with crystalline domains and point out the design rules to optimize the mixing phase structure,which is an effective approach to further improve device performance.

The structure and magnetic properties of β-(Ga_(0.96)Mn_(0.04))_2O_3 thin film

High quality epitaxial single phase（Ga_（0.96）Mn_（0.04））_2O_3 and Ga_2O_3 thin films have been prepared on sapphire substrates by using laser molecular b（eam）epitaxy（L-MBE）. X-ray diffraction results indicate that the thin films have the monoclinic structure with a 201 preferable orientation. Room temperature（RT） ferromagnetism appears and the magnetic properties of β-（Ga_（0.96）Mn_（0.04））_2O_3 thin film are enhanced compared with our previous works. Experiments as well as the first principle method are used to explain the role of Mn dopant on the structure and magnetic properties of the thin films. The ferromagnetic properties are explained based on the concentration of transition element and the defects in the thin films.