用 H2 和 Ga_2O_3的高温反应形成元素 Ga 的恒定表面源,通过 SiO_2-Si 复合结构实现了 Ga 在 Si 中的高均匀性掺杂;利用二次离子质谱分析(SIMS)、扩展电阻(SRP)、四探针测试等方法,对 P 型杂质 Ga 在 SiO_2薄膜、SiO_2-Si 两固相接触的...用 H2 和 Ga_2O_3的高温反应形成元素 Ga 的恒定表面源,通过 SiO_2-Si 复合结构实现了 Ga 在 Si 中的高均匀性掺杂;利用二次离子质谱分析(SIMS)、扩展电阻(SRP)、四探针测试等方法,对 P 型杂质 Ga 在 SiO_2薄膜、SiO_2-Si 两固相接触的内界面、近 Si 表面的热分布进行分析;揭示出开管方式扩散 Ga 的实质是由 SiO_2薄膜对 Ga 原子的快速输运及其在 SiO_2-Si 内界面分凝效应两者统一的必然结果;并对该过程 Ga 杂质浓度分布机理进行了分析和讨论。展开更多
Total dose effects and single event effects on radiation-hardened power vertical double-diffusion metal oxide semiconductor（VDMOS） devices with composite SiO2-Si3N4 film gates are investigated.The relationships amon...Total dose effects and single event effects on radiation-hardened power vertical double-diffusion metal oxide semiconductor（VDMOS） devices with composite SiO2-Si3N4 film gates are investigated.The relationships among the important electrical parameters of the samples with different thickness SiO2-Si3N4 films,such as threshold voltage,breakdown voltage,and on-state resistance in accumulated dose,are discussed.The total dose experiment results show that the breakdown voltage and the on-state resistance barely change with the accumulated dose.However,the relationships between the threshold voltages of the samples and the accumulated dose are more complex,and not only positively drift,but also negatively drift.At the end of the total dose experiment,we select the group of samples which have the smaller threshold voltage shift to carry out the single event effect studies.We find that the samples with appropriate thickness ratio SiO2-Si3N4 films have a good radiation-hardening ability.This method may be useful in solving both the SEGR and the total dose problems with the composite SiO2-Si3N4 films.展开更多
Mo（CO）6 adsorption on the clean, oxygen-precovered and deeply oxidized Si（lll） surfaces was comparatively investigated by high-resolution electron energy loss spectroscopy. The downward vibrational frequency shift...Mo（CO）6 adsorption on the clean, oxygen-precovered and deeply oxidized Si（lll） surfaces was comparatively investigated by high-resolution electron energy loss spectroscopy. The downward vibrational frequency shift of the C-O stretching mode in adsorbed Mo（CO）6 illustrates that different interactions of adsorbed Mo（CO）6 occur on clean Si（111） and SiO2/Si（111） surfaces, weak on the former and strong on the latter. The strong interaction on SiO2/Si（111） might lead to the partial dissociation of Mo（CO）6, consequently the formation of molybdenum subcarbonyls. Therefore, employing Mo（CO）6 as the precursor, metallic molybdenum could be successfully deposited on the SiO2/Si（111） surface but not on the clean Si（111） surface. A portion of the deposited metallic molybdenum is transformed into the MoOa on the SiO2/Si（111） surface upon heating, and the evolved MoO3 finally desorbs from the substrate upon annealing at elevated temperatures.展开更多
The energy deposition for low-energy electron beam on Si-SiO2 models was calculated by Monte-Carlo method. Making use of electron paramagnetic resonance (EPR) technique, an investigation of the effect of dopant type a...The energy deposition for low-energy electron beam on Si-SiO2 models was calculated by Monte-Carlo method. Making use of electron paramagnetic resonance (EPR) technique, an investigation of the effect of dopant type and concentration on EPR signal variations was carried out by using p-type and n-type silicon(111) wafers with concentration of 1×1015 cm 3 and 1×1017 cm 3, and the changes of intensity of defect paramagnetic centers before and after irradiation of electrons were compared. The chemical states of Si-SiO2 structure were determined by X-ray photoelectrons spectroscopy(XPS). The results clearly indicate that the effects of dopant variations (type and concentration) are of obvious difference. Compared with p-type silicon, n-type silicon, especially with higher dopant concentration, tends to produce defect at the interface under low-energy electron irradiation with certain flux, which arises from the hole trapped on a nonbridging oxygen atom bonded to P. It is represented in the form of distinct changes of POHC intensity and P2P spectrum. According to the theoretical and experimental data, the relationship among electron energy deposition, chemical states of element Si at SiO2 -Si(111) interface, and radiation effect were analyzed and discussed.展开更多
Resistive random-access memory(RRAM)is a promising technology to develop nonvolatile memory and artificial synaptic devices for brain-inspired neuromorphic computing.Here,we have developed a STO:Ag/SiO_(2) bilayer bas...Resistive random-access memory(RRAM)is a promising technology to develop nonvolatile memory and artificial synaptic devices for brain-inspired neuromorphic computing.Here,we have developed a STO:Ag/SiO_(2) bilayer based memristor that has exhibited a filamentary resistive switching with stable endurance and long-term data retention ability.The memristor also exhibits a tunable resistance modulation under positive and negative pulse trains,which could fully mimic the potentiation and depression behavior like a bio-synapse.Several synaptic plasticity functions,including long-term potentiation(LTP)and long-term depression(LTD),paired-pulsed facilitation(PPF),spike-rate-dependent-plasticity(SRDP),and post-tetanic potentiation(PTP),are faithfully implemented with the fabricated memristor.Moreover,to demonstrate the feasibility of our memristor synapse for neuromorphic applications,spike-timedependent plasticity(STDP)is also investigated.Based on conductive atomic force microscopy observations and electrical transport model analyses,it can be concluded that it is the controlled formation and rupture of Ag filaments that are responsible for the resistive switching while exhibiting a switching ratio of~10;along with a good endurance and stability suitable for nonvolatile memory applications.Before fully electroforming,the gradual conductance modulation of Ag/STO:Ag/SiO_(2)/p^(++)-Si memristor can be realized,and the working mechanism could be explained by the succeeding growth and contraction of Ag filaments promoted by a redox reaction.This newly fabricated memristor may enable the development of nonvolatile memory and realize controllable resistance/weight modulation when applied as an artificial synapse for neuromorphic computing.展开更多
BiFeO3 (BFO) thin films were prepared on Pt(111)/TiO2/SiO2/Si(100) substrates by the pulsed-laser deposition (PLD) technique at a low temperature of 450℃. The XRD results indicate that the BFO thin films are of perov...BiFeO3 (BFO) thin films were prepared on Pt(111)/TiO2/SiO2/Si(100) substrates by the pulsed-laser deposition (PLD) technique at a low temperature of 450℃. The XRD results indicate that the BFO thin films are of perovskite structure with the presence of small amount of second phases. The oxygen pressures have great effect on the crystalline structures and dielectric properties of BFO thin films. The dielectric constant of the BFO thin films decreases with increasing oxygen pressures, achieving 186, 171 and 160 at the frequency of 104 Hz for the oxygen pressures of 0.666, 1.333 and 13.332 Pa, respectively. The BFO thin films prepared at the oxygen pressure of 0.666 Pa reveal a saturated hysteresis loop with the remanent polarization of 7.5 μC/cm2 and the coercive field of 176 kV/cm.展开更多
文摘用 H2 和 Ga_2O_3的高温反应形成元素 Ga 的恒定表面源,通过 SiO_2-Si 复合结构实现了 Ga 在 Si 中的高均匀性掺杂;利用二次离子质谱分析(SIMS)、扩展电阻(SRP)、四探针测试等方法,对 P 型杂质 Ga 在 SiO_2薄膜、SiO_2-Si 两固相接触的内界面、近 Si 表面的热分布进行分析;揭示出开管方式扩散 Ga 的实质是由 SiO_2薄膜对 Ga 原子的快速输运及其在 SiO_2-Si 内界面分凝效应两者统一的必然结果;并对该过程 Ga 杂质浓度分布机理进行了分析和讨论。
文摘Total dose effects and single event effects on radiation-hardened power vertical double-diffusion metal oxide semiconductor（VDMOS） devices with composite SiO2-Si3N4 film gates are investigated.The relationships among the important electrical parameters of the samples with different thickness SiO2-Si3N4 films,such as threshold voltage,breakdown voltage,and on-state resistance in accumulated dose,are discussed.The total dose experiment results show that the breakdown voltage and the on-state resistance barely change with the accumulated dose.However,the relationships between the threshold voltages of the samples and the accumulated dose are more complex,and not only positively drift,but also negatively drift.At the end of the total dose experiment,we select the group of samples which have the smaller threshold voltage shift to carry out the single event effect studies.We find that the samples with appropriate thickness ratio SiO2-Si3N4 films have a good radiation-hardening ability.This method may be useful in solving both the SEGR and the total dose problems with the composite SiO2-Si3N4 films.
基金Science Challenge Project(TZ2016003-1-105)CAEP Microsystem and THz Science and Technology Foundation(CAEPMT201501)National Basic Research Program of China(2011CB606405)。
文摘Mo（CO）6 adsorption on the clean, oxygen-precovered and deeply oxidized Si（lll） surfaces was comparatively investigated by high-resolution electron energy loss spectroscopy. The downward vibrational frequency shift of the C-O stretching mode in adsorbed Mo（CO）6 illustrates that different interactions of adsorbed Mo（CO）6 occur on clean Si（111） and SiO2/Si（111） surfaces, weak on the former and strong on the latter. The strong interaction on SiO2/Si（111） might lead to the partial dissociation of Mo（CO）6, consequently the formation of molybdenum subcarbonyls. Therefore, employing Mo（CO）6 as the precursor, metallic molybdenum could be successfully deposited on the SiO2/Si（111） surface but not on the clean Si（111） surface. A portion of the deposited metallic molybdenum is transformed into the MoOa on the SiO2/Si（111） surface upon heating, and the evolved MoO3 finally desorbs from the substrate upon annealing at elevated temperatures.
基金supported by Major Foundation for Development of Science and Technology of China Academy of Engineering Physics (No. 2007A02001)
文摘The energy deposition for low-energy electron beam on Si-SiO2 models was calculated by Monte-Carlo method. Making use of electron paramagnetic resonance (EPR) technique, an investigation of the effect of dopant type and concentration on EPR signal variations was carried out by using p-type and n-type silicon(111) wafers with concentration of 1×1015 cm 3 and 1×1017 cm 3, and the changes of intensity of defect paramagnetic centers before and after irradiation of electrons were compared. The chemical states of Si-SiO2 structure were determined by X-ray photoelectrons spectroscopy(XPS). The results clearly indicate that the effects of dopant variations (type and concentration) are of obvious difference. Compared with p-type silicon, n-type silicon, especially with higher dopant concentration, tends to produce defect at the interface under low-energy electron irradiation with certain flux, which arises from the hole trapped on a nonbridging oxygen atom bonded to P. It is represented in the form of distinct changes of POHC intensity and P2P spectrum. According to the theoretical and experimental data, the relationship among electron energy deposition, chemical states of element Si at SiO2 -Si(111) interface, and radiation effect were analyzed and discussed.
基金financially supported by the National Science Funds for Excellent Young Scholars of China(no.61822106)the Natural Science Foundation of China(no.U19A2070)。
文摘Resistive random-access memory(RRAM)is a promising technology to develop nonvolatile memory and artificial synaptic devices for brain-inspired neuromorphic computing.Here,we have developed a STO:Ag/SiO_(2) bilayer based memristor that has exhibited a filamentary resistive switching with stable endurance and long-term data retention ability.The memristor also exhibits a tunable resistance modulation under positive and negative pulse trains,which could fully mimic the potentiation and depression behavior like a bio-synapse.Several synaptic plasticity functions,including long-term potentiation(LTP)and long-term depression(LTD),paired-pulsed facilitation(PPF),spike-rate-dependent-plasticity(SRDP),and post-tetanic potentiation(PTP),are faithfully implemented with the fabricated memristor.Moreover,to demonstrate the feasibility of our memristor synapse for neuromorphic applications,spike-timedependent plasticity(STDP)is also investigated.Based on conductive atomic force microscopy observations and electrical transport model analyses,it can be concluded that it is the controlled formation and rupture of Ag filaments that are responsible for the resistive switching while exhibiting a switching ratio of~10;along with a good endurance and stability suitable for nonvolatile memory applications.Before fully electroforming,the gradual conductance modulation of Ag/STO:Ag/SiO_(2)/p^(++)-Si memristor can be realized,and the working mechanism could be explained by the succeeding growth and contraction of Ag filaments promoted by a redox reaction.This newly fabricated memristor may enable the development of nonvolatile memory and realize controllable resistance/weight modulation when applied as an artificial synapse for neuromorphic computing.
基金Project (50472098) supported by the National Natural Science Foundation of China
文摘BiFeO3 (BFO) thin films were prepared on Pt(111)/TiO2/SiO2/Si(100) substrates by the pulsed-laser deposition (PLD) technique at a low temperature of 450℃. The XRD results indicate that the BFO thin films are of perovskite structure with the presence of small amount of second phases. The oxygen pressures have great effect on the crystalline structures and dielectric properties of BFO thin films. The dielectric constant of the BFO thin films decreases with increasing oxygen pressures, achieving 186, 171 and 160 at the frequency of 104 Hz for the oxygen pressures of 0.666, 1.333 and 13.332 Pa, respectively. The BFO thin films prepared at the oxygen pressure of 0.666 Pa reveal a saturated hysteresis loop with the remanent polarization of 7.5 μC/cm2 and the coercive field of 176 kV/cm.
