This work demonstrates high-performance NiO/β-Ga_(2)O_(3) vertical heterojunction diodes(HJDs)with double-layer junc-tion termination extension(DL-JTE)consisting of two p-typed NiO layers with varied lengths.The bott...This work demonstrates high-performance NiO/β-Ga_(2)O_(3) vertical heterojunction diodes(HJDs)with double-layer junc-tion termination extension(DL-JTE)consisting of two p-typed NiO layers with varied lengths.The bottom 60-nm p-NiO layer fully covers theβ-Ga_(2)O_(3) wafer,while the geometry of the upper 60-nm p-NiO layer is 10μm larger than the square anode elec-trode.Compared with a single-layer JTE,the electric field concentration is inhibited by double-layer JTE structure effectively,resulting in the breakdown voltage being improved from 2020 to 2830 V.Moreover,double p-typed NiO layers allow more holes into the Ga_(2)O_(3) drift layer to reduce drift resistance.The specific on-resistance is reduced from 1.93 to 1.34 mΩ·cm^(2).The device with DL-JTE shows a power figure-of-merit(PFOM)of 5.98 GW/cm^(2),which is 2.8 times larger than that of the conven-tional single-layer JTE structure.These results indicate that the double-layer JTE structure provides a viable way of fabricating high-performance Ga_(2)O_(3) HJDs.展开更多
In this work,a two-step metal organic chemical vapor deposition(MOCVD)method was applied for growingβ-Ga_(2)O_(3) film on c-plane sapphire.Optimized buffer layer growth temperature(T_(B))was found at 700℃ and theβ-...In this work,a two-step metal organic chemical vapor deposition(MOCVD)method was applied for growingβ-Ga_(2)O_(3) film on c-plane sapphire.Optimized buffer layer growth temperature(T_(B))was found at 700℃ and theβ-Ga_(2)O_(3) film with full width at half maximum(FWHM)of 0.66°was achieved.A metal−semiconductor−metal(MSM)solar-blind photodetector(PD)was fabricated based on theβ-Ga_(2)O_(3) film.Ultrahigh responsivity of 1422 A/W@254 nm and photo-to-dark current ratio(PDCR)of 10^(6) at 10 V bias were obtained.The detectivity of 2.5×10^(15) Jones proved that the photodetector has outstanding performance in detecting weak signals.Moreover,the photodetector exhibited superior wavelength selectivity with rejection ratio(R_(250 nm)/R_(400 nm))of 105.These results indicate that the two-step method is a promising approach for preparation of high-qualityβ-Ga_(2)O_(3)films for high-performance solar-blind photodetectors.展开更多
High qualityβ-Ga_(2)O_(3)single crystal nanobelts with length of 2−3 mm and width from tens of microns to 132μm were synthesized by carbothermal reduction method.Based on the grown nanobelt with the length of 600μm...High qualityβ-Ga_(2)O_(3)single crystal nanobelts with length of 2−3 mm and width from tens of microns to 132μm were synthesized by carbothermal reduction method.Based on the grown nanobelt with the length of 600μm,the dual-Schottky-junctions coupling device(DSCD)was fabricated.Due to the electrically floating Ga_(2)O_(3)nanobelt region coupling with the double Schottky-junctions,the current I_(S2)increases firstly and rapidly reaches into saturation as increase the voltage V_(S2).The saturation current is about 10 pA,which is two orders of magnitude lower than that of a single Schottky-junction.In the case of solar-blind ultraviolet(UV)light irradiation,the photogenerated electrons further aggravate the coupling physical mechanism in device.I_(S2)increases as the intensity of UV light increases.Under the UV light of 1820μW/cm^(2),I_(S2)quickly enters the saturation state.At V_(S2)=10 V,photo-to-dark current ratio(PDCR)of the device reaches more than 104,the external quantum efficiency(EQE)is 1.6×10^(3)%,and the detectivity(D*)is 7.5×10^(12)Jones.In addition,the device has a very short rise and decay times of 25−54 ms under different positive and negative bias.DSCD shows unique electrical and optical control characteristics,which will open a new way for the application of nanobelt-based devices.展开更多
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...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.展开更多
Ethane chemical looping oxidative dehydrogenation(CL-ODH)to ethylene is a new technology for ethylene preparation.Fe_(2)O_(3)/MgO oxygen carrier was prepared using the co-precipitation method.The influence of added Ni...Ethane chemical looping oxidative dehydrogenation(CL-ODH)to ethylene is a new technology for ethylene preparation.Fe_(2)O_(3)/MgO oxygen carrier was prepared using the co-precipitation method.The influence of added NiO and its different loadings on Fe_(2)O_(3)/MgO were investigated.Then,a series of oxygen carriers were applied in the CL-ODH of the ethane cycle system.Brunauer-Emmett-Teller(BET),X-ray diffractometry(XRD),X-ray photoelection spectroscopy(XPS),and H2-temperature programmed reduction(TPR)were used to characterize the physicochemical properties of these oxygen carriers.It was confirmed that an interaction between NiO and Fe_(2)O_(3) occurred based on the XPS and H2-TPR results.Based on the CL-ODH activity performance tests conducted in a fixed-bed reactor,it was revealed that ethylene selectivity was significantly improved after NiO addition.Fe_(2)O_(3)-10%NiO/MgO showed the best activity performance with 93%ethane conversion and 50%ethylene selectivity at a reaction temperature of 650℃,atmospheric pressure,and space velocity of 7500 mL/(g·h).展开更多
The 10 nm p-NiO thin film is prepared by thermal oxidation of Ni onβ-Ga_(2)O_(3)to form NiO/β-Ga_(2)O_(3)p-n heterojunction diodes(HJDs).The NiO/β-Ga_(2)O_(3)HJDs exhibit excellent electrostatic properties,with a h...The 10 nm p-NiO thin film is prepared by thermal oxidation of Ni onβ-Ga_(2)O_(3)to form NiO/β-Ga_(2)O_(3)p-n heterojunction diodes(HJDs).The NiO/β-Ga_(2)O_(3)HJDs exhibit excellent electrostatic properties,with a high breakdown voltage of 465 V,a specific on-resistance(Ron,sp)of 3.39 mΩ·cm^(2),and a turn-on voltage(V on)of 1.85 V,yielding a static Baliga's figure of merit(FOM)of 256 MW/cm^(2).Also,the HJDs have a low turn-on voltage,which reduces conduction loss dramatically,and a rectification ratio of up to 108.Meanwhile,the HJDs'reverse leakage current is essentially unaffected at temperatures below 170?C,and their leakage level may be controlled below 10^(-10)A.This indicates that p-NiO/β-Ga_(2)O_(3)HJDs with good thermal stability and high-temperature operating ability can be a good option for high-performanceβ-Ga_(2)O_(3)power devices.展开更多
A NiO/β-Ga_(2)O_(3) heterojunction-gate field effect transistor(HJ-FET)is fabricated and it_(s)instability mechanisms are exper-imentally investigated under different gate stress voltage(V_(G,s))and stress times(t_(s...A NiO/β-Ga_(2)O_(3) heterojunction-gate field effect transistor(HJ-FET)is fabricated and it_(s)instability mechanisms are exper-imentally investigated under different gate stress voltage(V_(G,s))and stress times(t_(s)).Two different degradation mechanisms of the devices under negative bias stress(NBS)are identified.At low V_(G,s)for a short t_(s),NiO bulk traps trapping/de-trapping elec-trons are responsible for decrease/recovery of the leakage current,respectively.At higher V_(G,s)or long t_(s),the device transfer char-acteristic curves and threshold voltage(V_(TH))are almost permanently negatively shifted.This is because the interface dipoles are almost permanently ionized and neutralize the ionized charges in the space charge region(SCR)across the heterojunction inter-face,resulting in a narrowing SCR.This provides an important theoretical guide to study the reliability of NiO/β-Ga_(2)O_(3) hetero-junction devices in power electronic applications.展开更多
基金supported by the National Natural Science Foundation of China under Grant U21A20503.
文摘This work demonstrates high-performance NiO/β-Ga_(2)O_(3) vertical heterojunction diodes(HJDs)with double-layer junc-tion termination extension(DL-JTE)consisting of two p-typed NiO layers with varied lengths.The bottom 60-nm p-NiO layer fully covers theβ-Ga_(2)O_(3) wafer,while the geometry of the upper 60-nm p-NiO layer is 10μm larger than the square anode elec-trode.Compared with a single-layer JTE,the electric field concentration is inhibited by double-layer JTE structure effectively,resulting in the breakdown voltage being improved from 2020 to 2830 V.Moreover,double p-typed NiO layers allow more holes into the Ga_(2)O_(3) drift layer to reduce drift resistance.The specific on-resistance is reduced from 1.93 to 1.34 mΩ·cm^(2).The device with DL-JTE shows a power figure-of-merit(PFOM)of 5.98 GW/cm^(2),which is 2.8 times larger than that of the conven-tional single-layer JTE structure.These results indicate that the double-layer JTE structure provides a viable way of fabricating high-performance Ga_(2)O_(3) HJDs.
基金This work was supported by the National Key Research and Development Program of China(Grant No.2020YFB2206103)。
文摘In this work,a two-step metal organic chemical vapor deposition(MOCVD)method was applied for growingβ-Ga_(2)O_(3) film on c-plane sapphire.Optimized buffer layer growth temperature(T_(B))was found at 700℃ and theβ-Ga_(2)O_(3) film with full width at half maximum(FWHM)of 0.66°was achieved.A metal−semiconductor−metal(MSM)solar-blind photodetector(PD)was fabricated based on theβ-Ga_(2)O_(3) film.Ultrahigh responsivity of 1422 A/W@254 nm and photo-to-dark current ratio(PDCR)of 10^(6) at 10 V bias were obtained.The detectivity of 2.5×10^(15) Jones proved that the photodetector has outstanding performance in detecting weak signals.Moreover,the photodetector exhibited superior wavelength selectivity with rejection ratio(R_(250 nm)/R_(400 nm))of 105.These results indicate that the two-step method is a promising approach for preparation of high-qualityβ-Ga_(2)O_(3)films for high-performance solar-blind photodetectors.
基金supported by Natural Science Basic Research Program in Shaanxi Province of China(No.2023-JCYB-574)National Natural Science Foundation of China(No.62204203).
文摘High qualityβ-Ga_(2)O_(3)single crystal nanobelts with length of 2−3 mm and width from tens of microns to 132μm were synthesized by carbothermal reduction method.Based on the grown nanobelt with the length of 600μm,the dual-Schottky-junctions coupling device(DSCD)was fabricated.Due to the electrically floating Ga_(2)O_(3)nanobelt region coupling with the double Schottky-junctions,the current I_(S2)increases firstly and rapidly reaches into saturation as increase the voltage V_(S2).The saturation current is about 10 pA,which is two orders of magnitude lower than that of a single Schottky-junction.In the case of solar-blind ultraviolet(UV)light irradiation,the photogenerated electrons further aggravate the coupling physical mechanism in device.I_(S2)increases as the intensity of UV light increases.Under the UV light of 1820μW/cm^(2),I_(S2)quickly enters the saturation state.At V_(S2)=10 V,photo-to-dark current ratio(PDCR)of the device reaches more than 104,the external quantum efficiency(EQE)is 1.6×10^(3)%,and the detectivity(D*)is 7.5×10^(12)Jones.In addition,the device has a very short rise and decay times of 25−54 ms under different positive and negative bias.DSCD shows unique electrical and optical control characteristics,which will open a new way for the application of nanobelt-based devices.
基金supported by BUPT Excellent Ph.D. Students Foundation (CX2023301)in part by the National Natural Science Foundation of China (62204019)
文摘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.
文摘Ethane chemical looping oxidative dehydrogenation(CL-ODH)to ethylene is a new technology for ethylene preparation.Fe_(2)O_(3)/MgO oxygen carrier was prepared using the co-precipitation method.The influence of added NiO and its different loadings on Fe_(2)O_(3)/MgO were investigated.Then,a series of oxygen carriers were applied in the CL-ODH of the ethane cycle system.Brunauer-Emmett-Teller(BET),X-ray diffractometry(XRD),X-ray photoelection spectroscopy(XPS),and H2-temperature programmed reduction(TPR)were used to characterize the physicochemical properties of these oxygen carriers.It was confirmed that an interaction between NiO and Fe_(2)O_(3) occurred based on the XPS and H2-TPR results.Based on the CL-ODH activity performance tests conducted in a fixed-bed reactor,it was revealed that ethylene selectivity was significantly improved after NiO addition.Fe_(2)O_(3)-10%NiO/MgO showed the best activity performance with 93%ethane conversion and 50%ethylene selectivity at a reaction temperature of 650℃,atmospheric pressure,and space velocity of 7500 mL/(g·h).
基金the Technology Innovation and Application Demonstration Key Project of Chongqing Municipality(cstc2019jszx-zdztzxX0005)the Technology Innovation and Application Demonstration Key Project of Chongqing Municipality(cstc2020jscx-gksbX0011)+1 种基金the Science and Technology Research Program of Chongqing Municipal Education Commission(KJQN202100614)the Natural Science Foundation of Chongqing(cstc2021jcyj-bshX0146)。
文摘The 10 nm p-NiO thin film is prepared by thermal oxidation of Ni onβ-Ga_(2)O_(3)to form NiO/β-Ga_(2)O_(3)p-n heterojunction diodes(HJDs).The NiO/β-Ga_(2)O_(3)HJDs exhibit excellent electrostatic properties,with a high breakdown voltage of 465 V,a specific on-resistance(Ron,sp)of 3.39 mΩ·cm^(2),and a turn-on voltage(V on)of 1.85 V,yielding a static Baliga's figure of merit(FOM)of 256 MW/cm^(2).Also,the HJDs have a low turn-on voltage,which reduces conduction loss dramatically,and a rectification ratio of up to 108.Meanwhile,the HJDs'reverse leakage current is essentially unaffected at temperatures below 170?C,and their leakage level may be controlled below 10^(-10)A.This indicates that p-NiO/β-Ga_(2)O_(3)HJDs with good thermal stability and high-temperature operating ability can be a good option for high-performanceβ-Ga_(2)O_(3)power devices.
基金supported by the Fundamental Strengthening Program Key Basic Research Project(Grant No.2021-173ZD-057).
文摘A NiO/β-Ga_(2)O_(3) heterojunction-gate field effect transistor(HJ-FET)is fabricated and it_(s)instability mechanisms are exper-imentally investigated under different gate stress voltage(V_(G,s))and stress times(t_(s)).Two different degradation mechanisms of the devices under negative bias stress(NBS)are identified.At low V_(G,s)for a short t_(s),NiO bulk traps trapping/de-trapping elec-trons are responsible for decrease/recovery of the leakage current,respectively.At higher V_(G,s)or long t_(s),the device transfer char-acteristic curves and threshold voltage(V_(TH))are almost permanently negatively shifted.This is because the interface dipoles are almost permanently ionized and neutralize the ionized charges in the space charge region(SCR)across the heterojunction inter-face,resulting in a narrowing SCR.This provides an important theoretical guide to study the reliability of NiO/β-Ga_(2)O_(3) hetero-junction devices in power electronic applications.
