In this paper,we propose a near-infrared p-type β-FeSi2/n-type 4H-SiC heterojunction photodetector with semiconducting silicide（β-FeSi2） as the active region for the first time.The optoelectronic characteristics o...In this paper,we propose a near-infrared p-type β-FeSi2/n-type 4H-SiC heterojunction photodetector with semiconducting silicide（β-FeSi2） as the active region for the first time.The optoelectronic characteristics of the photodetector are simulated using a commercial simulator at room temperature.The results show that the photodetector has a good rectifying character and a good response to near-infrared light.Interface states should be minimized to obtain a lower reverse leakage current.The response spectrum of the β-FeSi2/4H-SiC detector,which consists of a p-type β-FeSi2 absorption layer with a doping concentration of 1×1015cm-3 and a thickness of 2.5 μm,has a peak of 755 mA/W at 1.42 μm.The illumination of the SiC side obtains a higher responsivity than that of the β-FeSi2 side.The results illustrate that the β-FeSi2/4H-SiC heterojunction can be used as a near-infrared photodetector compatible with near-infrared optically-activated SiC-based power switching devices.展开更多
High-k materials as an alternative dielectric layer for SiC power devices have the potential to reduce interfacial state defects and improve MOS channel conduction capability.Besides,under identical conditions of gate...High-k materials as an alternative dielectric layer for SiC power devices have the potential to reduce interfacial state defects and improve MOS channel conduction capability.Besides,under identical conditions of gate oxide thickness and gate voltage,the high-k dielectric enables a greater charge accumulation in the channel region,resulting in a larger number of free electrons available for conduction.However,the lower energy band gap of high-k materials leads to significant leakage currents at the interface with Si C,which greatly affects device reliability.By inserting a layer of SiO_(2)between the high-k material and Si C,the interfacial barrier can be effectively widened and hence the leakage current will be reduced.In this study,the optimal thickness of the intercalated SiO_(2)was determined by investigating and analyzing the gate dielectric breakdown voltage and interfacial defects of a dielectric stack composed of atomic-layer-deposited Al_(2)O_(3)layer and thermally nitride SiO_(2).Current-voltage and high-frequency capacitance-voltage measurements were performed on metal-oxide-semiconductor test structures with 35 nm thick Al_(2)O_(3)stacked on 1 nm,2 nm,3 nm,6 nm,or 9 nm thick nitride SiO_(2).Measurement results indicated that the current conducted through the oxides was affected by the thickness of the nitride oxide and the applied electric field.Finally,a saturation thickness of stacked SiO_(2)that contributed to dielectric breakdown and interfacial band offsets was identified.The findings in this paper provide a guideline for the SiC gate dielectric stack design with the breakdown strength and the interfacial state defects considered.展开更多
Atomic layer deposited （ALD） Al2O3/dry-oxidized ultrathin SiO2 films as a high-k gate dielectric grown on 8° off-axis 4H-SiC （0001） epitaxial wafers are investigated in this paper. The metal-insulation-semico...Atomic layer deposited （ALD） Al2O3/dry-oxidized ultrathin SiO2 films as a high-k gate dielectric grown on 8° off-axis 4H-SiC （0001） epitaxial wafers are investigated in this paper. The metal-insulation-semiconductor （MIS） capacitors, respectively with different gate dielectric stacks （Al2O3/SiO2, Al2O3, and SiO2） are fabricated and compared with each other. The I-V measurements show that the Al2O3/SiO2 stack has a high breakdown field （≥12 MV/cm） comparable to SiO2, and a relatively low gate leakage current of 1 × 10-7 A/cm2 at an electric field of 4 MV/cm comparable to Al2O3. The 1-MHz high frequency C-V measurements exhibit that the Al2O3/SiO2 stack has a smaller positive flat-band voltage shift and hysteresis voltage, indicating a less effective charge and slow-trap density near the interface.展开更多
The compound （SiCl3）2Fe（CO）4 was synthesized and structurally characterized by X-ray single-crystal diffraction. It crystallizes in monoclinic, space group P2 1/n with α = 8.287（2）, b = 9.829（2）, c = 9.042（2...The compound （SiCl3）2Fe（CO）4 was synthesized and structurally characterized by X-ray single-crystal diffraction. It crystallizes in monoclinic, space group P2 1/n with α = 8.287（2）, b = 9.829（2）, c = 9.042（2） A, β = 96.19（3）°, V= 732.2（3） A^3, C4Cl6FeO4Si2, Mr = 436.77, Z = 2, Dc = 1.981 g/cm^3, F（000） = 424, μ（MoKα） = 2.282 mm^-1, the final R = 0.048 and wR = 0.164 for 1109 observed reflections （I 〉 2σ（I））. The crystal structure of （SiCl3）2Fe（CO）4 reveals that the Si（l）- Fe-Si（l）^a sequence is linear and perpendicular to the Fe（CO）4 cross-shaped plane.展开更多
We give the first report on the experimental investigation of a p-β-FeSi2/n-4H-SiC heterojunction. A β-/%FeSiE/n-4H-SiC heterojunction near-infrared photodiode was fabricated on 4H-SiC substrate by magnetron sputter...We give the first report on the experimental investigation of a p-β-FeSi2/n-4H-SiC heterojunction. A β-/%FeSiE/n-4H-SiC heterojunction near-infrared photodiode was fabricated on 4H-SiC substrate by magnetron sputtering and rapid thermal annealing （RTA）. Sharp film-substrate interfaces were confirmed by scanning elec-tron microscopy （SEM）. The current density-voltage and photoresponse characteristics were measured. The measurements showed that the device exhibited good rectifying properties. The photocurrent density was about 1.82 mA/cm^2 at a bias voltage of -1 V under illumination by a 5 mW, 1.31 μm laser, and the dark current density was approximately 0.537 mA/cm^2. The detectivity was estimated to be 8.8×10^9 cmHzl/2/W at 1.31 μm. All of the measurements were made at room temperature. The results suggest that the p-β-FeSiE/n-4H-SiC heterojunctions can be used as near-infrared photodiodes that are applicable to optically-activated SiC-based devices.展开更多
β-FeSi2 thin films have been successfully prepared by magnetron sputtering and post rapid thermal annealing method on 6H-SiC （0001） substrates using a FeSi2 target and a Si target. X-ray diffraction （XRD） and Ram...β-FeSi2 thin films have been successfully prepared by magnetron sputtering and post rapid thermal annealing method on 6H-SiC （0001） substrates using a FeSi2 target and a Si target. X-ray diffraction （XRD） and Raman spectroscopy are applied to analyze the formation of/%FeSi2 films. XRD spectra reveal that the amorphous FeSi2 films are transformed to%FeSi2 phase as the annealing temperature is increased from 500 to 900 ℃ for 5 min and the optimal annealing temperature is 900 ℃. The formation of β-FeSi2 is also confirmed by Raman spectroscopy. Scanning electron microscope （SEM） observations indicate that the film is βat, relatively compact and the interface between β-FeSi2 and 6H-SiC is clear. Atomic force microscope （AFM） measurements demonstrate that the surface roughness confirmed by the root mean square （RMS） of the tJ-FeSi2 film is 0.87 nm. Near-infrared spectrophotometer observation shows that the absorption coefficient is of the order of 105 cm-1 and the optical band-gap of the β-FeSi2 film is 0.88 eV. The β-FeSi2 film with high crystal quality is fabricated by co-sputtering a FeSi2 target and a Si target for 60 min and annealing at 900 ℃ for 5 min.展开更多
The interface properties of 4H-SiC metal oxide semiconductor （MOS） capacitors with post-oxidation annealing （POA） in nitric oxide （NO） ambient after high temperature （1300 ℃） oxidation have been investigated ...The interface properties of 4H-SiC metal oxide semiconductor （MOS） capacitors with post-oxidation annealing （POA） in nitric oxide （NO） ambient after high temperature （1300 ℃） oxidation have been investigated using capacitance-voltage （C V） measurements. The experimental results show that the interface states density （Dit） can be obviously decreased by the POA in NO ambient （NO-POA） and further reduced with increasing POA temperature and time. In the meantime significant reduction of the interface states density and oxidation time can be achieved at the higher thermal oxidation temperature, which results in the better oxide MOS characteristics and lower production costs. The dependence of Dit on POA temperature and time has been also discussed in detail.展开更多
Field plate(FP)-terminated 4H-SiC trench gate MOSFETs are demonstrated in this work.N+/P?/N?/N+multiple epitaxial layers were grown on 3-inch N+type 4H-SiC substrate by chemical vapor deposition(CVD),and then the 4H-S...Field plate(FP)-terminated 4H-SiC trench gate MOSFETs are demonstrated in this work.N+/P?/N?/N+multiple epitaxial layers were grown on 3-inch N+type 4H-SiC substrate by chemical vapor deposition(CVD),and then the 4H-SiC trench gate MOSFETs were fabricated based on the standard trench transistor fabrication.Current-voltage measurements in forward and reverse bias have been performed on different devices with and without FP protections.It is found that more than 60%of the devices protected with FP termination are able to block 850 V.The measurements also show that the devices have the small leakage currents 0.15 nA at 600 V and 2.5 nA at 800 V,respectively.The experimental results also were compared with the simulated results,which show good agreement with each other in the trend.The limited performance of the devices is mainly because of the damage induced on the trench sidewalls from the etching process and the quality of the SiO2 films.Therefore,the 4H-SiC trench gate MOSFETs are expected to be optimized by reducing the etching damage and growing high-quality SiO2 dielectric films.展开更多
The characteristics of 4H-SiC PiN diodes with a carbon-implanted drift layer was investigated and the reason of characteristics improvement was analyzed. The forward voltage drops of the diodes with carbonimplanted dr...The characteristics of 4H-SiC PiN diodes with a carbon-implanted drift layer was investigated and the reason of characteristics improvement was analyzed. The forward voltage drops of the diodes with carbonimplanted drift layer were around 3.3 V, which is lower than that of devices without carbon implantation, the specific-on resistance was decreased from 9.35 to 4.38 mΩcm^2 at 100 A/cm^2, and the reverse leakage current was also decreased. The influence of carbon incorporation in the Si C crystalline grids was studied by using deep-level transient spectroscopy（DLTS）. The DLTS spectra revealed that the Z_（1/2） traps, which were regarded as the main lifetime limiting defects, were dramatically reduced. It is proposed that the reduction of Z_（1/2） traps can achieve longer carrier lifetime in the drift layer, which is beneficial to the performance of bipolar devices.展开更多
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 60876050 and 51177134)
文摘In this paper,we propose a near-infrared p-type β-FeSi2/n-type 4H-SiC heterojunction photodetector with semiconducting silicide（β-FeSi2） as the active region for the first time.The optoelectronic characteristics of the photodetector are simulated using a commercial simulator at room temperature.The results show that the photodetector has a good rectifying character and a good response to near-infrared light.Interface states should be minimized to obtain a lower reverse leakage current.The response spectrum of the β-FeSi2/4H-SiC detector,which consists of a p-type β-FeSi2 absorption layer with a doping concentration of 1×1015cm-3 and a thickness of 2.5 μm,has a peak of 755 mA/W at 1.42 μm.The illumination of the SiC side obtains a higher responsivity than that of the β-FeSi2 side.The results illustrate that the β-FeSi2/4H-SiC heterojunction can be used as a near-infrared photodetector compatible with near-infrared optically-activated SiC-based power switching devices.
基金Project supported by the Key Area Research and Development Program of Guangdong Province of China(Grant No.2021B0101300005)the National Key Research and Development Program of China(Grant No.2021YFB3401603)。
文摘High-k materials as an alternative dielectric layer for SiC power devices have the potential to reduce interfacial state defects and improve MOS channel conduction capability.Besides,under identical conditions of gate oxide thickness and gate voltage,the high-k dielectric enables a greater charge accumulation in the channel region,resulting in a larger number of free electrons available for conduction.However,the lower energy band gap of high-k materials leads to significant leakage currents at the interface with Si C,which greatly affects device reliability.By inserting a layer of SiO_(2)between the high-k material and Si C,the interfacial barrier can be effectively widened and hence the leakage current will be reduced.In this study,the optimal thickness of the intercalated SiO_(2)was determined by investigating and analyzing the gate dielectric breakdown voltage and interfacial defects of a dielectric stack composed of atomic-layer-deposited Al_(2)O_(3)layer and thermally nitride SiO_(2).Current-voltage and high-frequency capacitance-voltage measurements were performed on metal-oxide-semiconductor test structures with 35 nm thick Al_(2)O_(3)stacked on 1 nm,2 nm,3 nm,6 nm,or 9 nm thick nitride SiO_(2).Measurement results indicated that the current conducted through the oxides was affected by the thickness of the nitride oxide and the applied electric field.Finally,a saturation thickness of stacked SiO_(2)that contributed to dielectric breakdown and interfacial band offsets was identified.The findings in this paper provide a guideline for the SiC gate dielectric stack design with the breakdown strength and the interfacial state defects considered.
基金Project supported by the National Natural Science Foundation of China （Grant Nos. 61006060 and 61176070）.
文摘Atomic layer deposited （ALD） Al2O3/dry-oxidized ultrathin SiO2 films as a high-k gate dielectric grown on 8° off-axis 4H-SiC （0001） epitaxial wafers are investigated in this paper. The metal-insulation-semiconductor （MIS） capacitors, respectively with different gate dielectric stacks （Al2O3/SiO2, Al2O3, and SiO2） are fabricated and compared with each other. The I-V measurements show that the Al2O3/SiO2 stack has a high breakdown field （≥12 MV/cm） comparable to SiO2, and a relatively low gate leakage current of 1 × 10-7 A/cm2 at an electric field of 4 MV/cm comparable to Al2O3. The 1-MHz high frequency C-V measurements exhibit that the Al2O3/SiO2 stack has a smaller positive flat-band voltage shift and hysteresis voltage, indicating a less effective charge and slow-trap density near the interface.
基金supported by the 863 Project (2006 A03Z219)Natural Science Foundation of Jiangsu Province (BK2007199)+2 种基金Foundation for "Liu Da Ren Cai" of Jiangsu Province (06-E-021)State Postdoctoral Foundation of China (No. 2006040932)the Postdoctoral Foundation of Jiangsu Province (No. 0602008B)
文摘The compound （SiCl3）2Fe（CO）4 was synthesized and structurally characterized by X-ray single-crystal diffraction. It crystallizes in monoclinic, space group P2 1/n with α = 8.287（2）, b = 9.829（2）, c = 9.042（2） A, β = 96.19（3）°, V= 732.2（3） A^3, C4Cl6FeO4Si2, Mr = 436.77, Z = 2, Dc = 1.981 g/cm^3, F（000） = 424, μ（MoKα） = 2.282 mm^-1, the final R = 0.048 and wR = 0.164 for 1109 observed reflections （I 〉 2σ（I））. The crystal structure of （SiCl3）2Fe（CO）4 reveals that the Si（l）- Fe-Si（l）^a sequence is linear and perpendicular to the Fe（CO）4 cross-shaped plane.
基金Project supported by the National Natural Science Foundation of China(No.51177134)
文摘We give the first report on the experimental investigation of a p-β-FeSi2/n-4H-SiC heterojunction. A β-/%FeSiE/n-4H-SiC heterojunction near-infrared photodiode was fabricated on 4H-SiC substrate by magnetron sputtering and rapid thermal annealing （RTA）. Sharp film-substrate interfaces were confirmed by scanning elec-tron microscopy （SEM）. The current density-voltage and photoresponse characteristics were measured. The measurements showed that the device exhibited good rectifying properties. The photocurrent density was about 1.82 mA/cm^2 at a bias voltage of -1 V under illumination by a 5 mW, 1.31 μm laser, and the dark current density was approximately 0.537 mA/cm^2. The detectivity was estimated to be 8.8×10^9 cmHzl/2/W at 1.31 μm. All of the measurements were made at room temperature. The results suggest that the p-β-FeSiE/n-4H-SiC heterojunctions can be used as near-infrared photodiodes that are applicable to optically-activated SiC-based devices.
基金Project supported by the National Natural Science Foundation of China(No.51177134)the Natural Science Basic Research Plan in Shaanxi Province of China(No.2015JM6286)
文摘β-FeSi2 thin films have been successfully prepared by magnetron sputtering and post rapid thermal annealing method on 6H-SiC （0001） substrates using a FeSi2 target and a Si target. X-ray diffraction （XRD） and Raman spectroscopy are applied to analyze the formation of/%FeSi2 films. XRD spectra reveal that the amorphous FeSi2 films are transformed to%FeSi2 phase as the annealing temperature is increased from 500 to 900 ℃ for 5 min and the optimal annealing temperature is 900 ℃. The formation of β-FeSi2 is also confirmed by Raman spectroscopy. Scanning electron microscope （SEM） observations indicate that the film is βat, relatively compact and the interface between β-FeSi2 and 6H-SiC is clear. Atomic force microscope （AFM） measurements demonstrate that the surface roughness confirmed by the root mean square （RMS） of the tJ-FeSi2 film is 0.87 nm. Near-infrared spectrophotometer observation shows that the absorption coefficient is of the order of 105 cm-1 and the optical band-gap of the β-FeSi2 film is 0.88 eV. The β-FeSi2 film with high crystal quality is fabricated by co-sputtering a FeSi2 target and a Si target for 60 min and annealing at 900 ℃ for 5 min.
基金Project supported by the National Natural Science Foundation of China(No.61234006)the State Grid of China(No.sgri-wd-71-14-003)
文摘The interface properties of 4H-SiC metal oxide semiconductor （MOS） capacitors with post-oxidation annealing （POA） in nitric oxide （NO） ambient after high temperature （1300 ℃） oxidation have been investigated using capacitance-voltage （C V） measurements. The experimental results show that the interface states density （Dit） can be obviously decreased by the POA in NO ambient （NO-POA） and further reduced with increasing POA temperature and time. In the meantime significant reduction of the interface states density and oxidation time can be achieved at the higher thermal oxidation temperature, which results in the better oxide MOS characteristics and lower production costs. The dependence of Dit on POA temperature and time has been also discussed in detail.
基金supported by the National Natural Science Foundation of China(Grant Nos.61176070,61274079)the Natural Science Foundation of Shaanxi Province(Grant No.2013JQ8012)+1 种基金the Doctoral Fund of Ministry of Education of China(Grant Nos.20110203110010,201302031-0017)the Key Specific Projects of Ministry of Education of China(Grant No.625010101)
文摘Field plate(FP)-terminated 4H-SiC trench gate MOSFETs are demonstrated in this work.N+/P?/N?/N+multiple epitaxial layers were grown on 3-inch N+type 4H-SiC substrate by chemical vapor deposition(CVD),and then the 4H-SiC trench gate MOSFETs were fabricated based on the standard trench transistor fabrication.Current-voltage measurements in forward and reverse bias have been performed on different devices with and without FP protections.It is found that more than 60%of the devices protected with FP termination are able to block 850 V.The measurements also show that the devices have the small leakage currents 0.15 nA at 600 V and 2.5 nA at 800 V,respectively.The experimental results also were compared with the simulated results,which show good agreement with each other in the trend.The limited performance of the devices is mainly because of the damage induced on the trench sidewalls from the etching process and the quality of the SiO2 films.Therefore,the 4H-SiC trench gate MOSFETs are expected to be optimized by reducing the etching damage and growing high-quality SiO2 dielectric films.
基金Project supported by the Opening Project of Key Laboratory of Microelectronics Devices & Integrated Technology,Institute of Microelectronics,Chinese Academy of Sciences
文摘The characteristics of 4H-SiC PiN diodes with a carbon-implanted drift layer was investigated and the reason of characteristics improvement was analyzed. The forward voltage drops of the diodes with carbonimplanted drift layer were around 3.3 V, which is lower than that of devices without carbon implantation, the specific-on resistance was decreased from 9.35 to 4.38 mΩcm^2 at 100 A/cm^2, and the reverse leakage current was also decreased. The influence of carbon incorporation in the Si C crystalline grids was studied by using deep-level transient spectroscopy（DLTS）. The DLTS spectra revealed that the Z_（1/2） traps, which were regarded as the main lifetime limiting defects, were dramatically reduced. It is proposed that the reduction of Z_（1/2） traps can achieve longer carrier lifetime in the drift layer, which is beneficial to the performance of bipolar devices.
