Electron beams of 0.5, 1.5, 2.0, and 5.0 MeV were used to irradiate n-Si diodes to fluences of5.5×10^(13), 1.7×10^(14), and 3.3×1014 e cm^(-2). The forward voltage drop, minority carrier lifetime, and d...Electron beams of 0.5, 1.5, 2.0, and 5.0 MeV were used to irradiate n-Si diodes to fluences of5.5×10^(13), 1.7×10^(14), and 3.3×1014 e cm^(-2). The forward voltage drop, minority carrier lifetime, and deep level transient spectroscopy(DLTS) characteristics of silicon p–n junction diodes before and after irradiation were compared. At the fluence of 3.3×10^(14) e cm^(-2), the forward voltage drop increased from 1.25 V at 0.5 MeV to 7.96μs at 5.0 MeV, while the minority carrier lifetime decreased significantly from 7.09 ls at 0.5 MeV to 0.06μs at 5.0 MeV. Six types of changes in the energy levels in DLTS spectra were analyzed and discussed.展开更多
The Dit(interface states density)in p-type MOS capacitors subjected to a preoxidation heat treatment was investigated by using DLTS(Deep Level Transient Spectroscopy)technique.It is found that the strong dependence of...The Dit(interface states density)in p-type MOS capacitors subjected to a preoxidation heat treatment was investigated by using DLTS(Deep Level Transient Spectroscopy)technique.It is found that the strong dependence of the Dit on POHT(Preoxidation Heat Treatment)and starting oxygen content of substrates is expected.The DLTS technique can detects the presence of bulk defect(Et-Ev=0.29eV)at the interface presumably due to chlorine species.展开更多
We investigate high electron mobility transistors (HEMT’s) based on AlGaN/GaN grown by molecular beam epitaxy on Silicon substrates. The improvement of the performances of such transistors is still subject to the inf...We investigate high electron mobility transistors (HEMT’s) based on AlGaN/GaN grown by molecular beam epitaxy on Silicon substrates. The improvement of the performances of such transistors is still subject to the influence of threading dislocations and point defects which are commonly observed in these devices. Deep levels in FAT-HEMT’s are characterized by using Capacitance-Voltage (C-V) measurements, from which we can extract the barrier height and the donor concentration in the AlGaN layer. Deep Level Transient Spectroscopy (DLTS) Technique is also employed to identify defects in the heterostructure. Measurements reveal the presence of one electron trap with the activation energy E1 = 0.30 eV and capture cross-section σn = 3.59 10–19cm2. The localization and the identification of this trap have been discussed.展开更多
Radiation damage produced in 4H-SiC by electrons of different doses is presented by using multiple characterization techniques. Raman spectra results indicate that SiC crystal structures are essentially impervious to ...Radiation damage produced in 4H-SiC by electrons of different doses is presented by using multiple characterization techniques. Raman spectra results indicate that SiC crystal structures are essentially impervious to 10 Me V electron irradiation with doses up to 3000 kGy. However, irradiation indeed leads to the generation of various defects, which are evaluated through photoluminescence(PL) and deep level transient spectroscopy(DLTS). The PL spectra feature a prominent broad band centered at 500 nm, accompanied by several smaller peaks ranging from 660 to 808 nm. The intensity of each PL peak demonstrates a linear correlation with the irradiation dose, indicating a proportional increase in defect concentration during irradiation. The DLTS spectra reveal several thermally unstable and stable defects that exhibit similarities at low irradiation doses.Notably, after irradiating at the higher dose of 1000 kGy, a new stable defect labeled as R_(2)(Ec-0.51 eV) appeared after annealing at 800 K. Furthermore, the impact of irradiation-induced defects on SiC junction barrier Schottky diodes is discussed. It is observed that high-dose electron irradiation converts SiC n-epilayers to semi-insulating layers. However, subjecting the samples to a temperature of only 800 K results in a significant reduction in resistance due to the annealing out of unstable defects.展开更多
Trap characterization on GaN Schottky barrier diodes(SBDs)has been carried out using deep-level transient spectroscopy(DLTS).Selective probing by varying the ratio of the rate window values(r)incites different trap si...Trap characterization on GaN Schottky barrier diodes(SBDs)has been carried out using deep-level transient spectroscopy(DLTS).Selective probing by varying the ratio of the rate window values(r)incites different trap signatures at similar temperature regimes.Electron traps are found to be within the values:0.05–1.2 eV from the conduction band edge whereas the hole traps 1.37–2.66 eV from the valence band edge on the SBDs.In the lower temperature regime,the deeper electron traps contribute to the capacitance transients with increasing r values,whereas at the higher temperatures>300 K,a slow variation of the trap levels(both electrons and holes)is observed when r is varied.These traps are found to be mainly contributed to dislocations,interfaces,and vacancies within the structure.展开更多
基金supported by the Beijing education and scientific research department(No.KM201510005008)
文摘Electron beams of 0.5, 1.5, 2.0, and 5.0 MeV were used to irradiate n-Si diodes to fluences of5.5×10^(13), 1.7×10^(14), and 3.3×1014 e cm^(-2). The forward voltage drop, minority carrier lifetime, and deep level transient spectroscopy(DLTS) characteristics of silicon p–n junction diodes before and after irradiation were compared. At the fluence of 3.3×10^(14) e cm^(-2), the forward voltage drop increased from 1.25 V at 0.5 MeV to 7.96μs at 5.0 MeV, while the minority carrier lifetime decreased significantly from 7.09 ls at 0.5 MeV to 0.06μs at 5.0 MeV. Six types of changes in the energy levels in DLTS spectra were analyzed and discussed.
文摘The Dit(interface states density)in p-type MOS capacitors subjected to a preoxidation heat treatment was investigated by using DLTS(Deep Level Transient Spectroscopy)technique.It is found that the strong dependence of the Dit on POHT(Preoxidation Heat Treatment)and starting oxygen content of substrates is expected.The DLTS technique can detects the presence of bulk defect(Et-Ev=0.29eV)at the interface presumably due to chlorine species.
文摘We investigate high electron mobility transistors (HEMT’s) based on AlGaN/GaN grown by molecular beam epitaxy on Silicon substrates. The improvement of the performances of such transistors is still subject to the influence of threading dislocations and point defects which are commonly observed in these devices. Deep levels in FAT-HEMT’s are characterized by using Capacitance-Voltage (C-V) measurements, from which we can extract the barrier height and the donor concentration in the AlGaN layer. Deep Level Transient Spectroscopy (DLTS) Technique is also employed to identify defects in the heterostructure. Measurements reveal the presence of one electron trap with the activation energy E1 = 0.30 eV and capture cross-section σn = 3.59 10–19cm2. The localization and the identification of this trap have been discussed.
基金supported by the Open Fund(2022E10015)of the Key Laboratory of Power Semiconductor Materials and Devices of Zhejiang Province&Institute of Advanced Semiconductors,ZJU-Hangzhou Global Scientific and Technological Innovation Center。
文摘Radiation damage produced in 4H-SiC by electrons of different doses is presented by using multiple characterization techniques. Raman spectra results indicate that SiC crystal structures are essentially impervious to 10 Me V electron irradiation with doses up to 3000 kGy. However, irradiation indeed leads to the generation of various defects, which are evaluated through photoluminescence(PL) and deep level transient spectroscopy(DLTS). The PL spectra feature a prominent broad band centered at 500 nm, accompanied by several smaller peaks ranging from 660 to 808 nm. The intensity of each PL peak demonstrates a linear correlation with the irradiation dose, indicating a proportional increase in defect concentration during irradiation. The DLTS spectra reveal several thermally unstable and stable defects that exhibit similarities at low irradiation doses.Notably, after irradiating at the higher dose of 1000 kGy, a new stable defect labeled as R_(2)(Ec-0.51 eV) appeared after annealing at 800 K. Furthermore, the impact of irradiation-induced defects on SiC junction barrier Schottky diodes is discussed. It is observed that high-dose electron irradiation converts SiC n-epilayers to semi-insulating layers. However, subjecting the samples to a temperature of only 800 K results in a significant reduction in resistance due to the annealing out of unstable defects.
基金the financial support received from the Department of Science and Technology,India through DST-INSPIRE Faculty scheme(DST/INSPIRE/04/2015/001572).
文摘Trap characterization on GaN Schottky barrier diodes(SBDs)has been carried out using deep-level transient spectroscopy(DLTS).Selective probing by varying the ratio of the rate window values(r)incites different trap signatures at similar temperature regimes.Electron traps are found to be within the values:0.05–1.2 eV from the conduction band edge whereas the hole traps 1.37–2.66 eV from the valence band edge on the SBDs.In the lower temperature regime,the deeper electron traps contribute to the capacitance transients with increasing r values,whereas at the higher temperatures>300 K,a slow variation of the trap levels(both electrons and holes)is observed when r is varied.These traps are found to be mainly contributed to dislocations,interfaces,and vacancies within the structure.
