To date,the benchmark Bi_(2)Te_(3)-based alloys are still the only commercial material system used for ther-moelectric solid-state refrigeration.Nonetheless,the conspicuous performance imbalance between the p-type Bi_...To date,the benchmark Bi_(2)Te_(3)-based alloys are still the only commercial material system used for ther-moelectric solid-state refrigeration.Nonetheless,the conspicuous performance imbalance between the p-type Bi_(2-x)Sb_(x)Te_(3)and n-type Bi_(2)Te_(3-x)Se_(x) legs has become a major obstacle for the improvement of cooling devices to achieve higher efficiency.In our previous study,novel n-type Bi_(2-x)Sb_(x)Te_(3)alloy has been pro-posed via manipulating donor-like effect as an alternative to mainstream n-type Bi_(2)Te_(3-x)Se_(x).However,the narrow bandgap of Bi_(2-x)Sb_(x)Te_(3)provoked severe bipolar effect that constrained the further improvement of zT near room temperature.Herein,we have implemented band gap engineering in n-type Bi_(1.5)Sb_(0.5)Te_(3)by employing isovalent Se substitution to inhibit the undesired intrinsic excitation and achieve the dis-tinguished room-temperature zT.First,the preferential occupancy of Se at Te^(2)site appropriately enlarges the band gap,thereby concurrently improving the Seebeck coefficient and depressing the bipolar thermal conductivity.In addition,the Se alloying mildly suppresses the compensation mechanism and essentially preserves the already optimized carrier concentration,which maintains the peak zT near room tempera-ture.Moreover,the large strain field and mass fluctuation generated by Se alloying leads to the remark-able reduction of lattice thermal conductivity.Accordingly,the zT value of Bi_(1.5)Sb_(0.5)Te_(2.8)Se_(0.2)reaches 1.0 at 300 K and peaks 1.1 at 360 K,which surpasses that of most well-known room-temperature n-type thermoelectric materials.These results pave the way for n-type Bi_(2-x)Sb_(x)Te_(3)alloys to become a new and promising top candidate for large-scale solid-state cooling applications.展开更多
In this paper, a new method is proposed to study the mechanism of charge collection in single event transient （SET） production in 90 nm bulk complementary metal oxide semiconductor （CMOS） technology. We find that ...In this paper, a new method is proposed to study the mechanism of charge collection in single event transient （SET） production in 90 nm bulk complementary metal oxide semiconductor （CMOS） technology. We find that different from the case in the pMOSFET, the parasitic bipolar amplification effect （bipolar effect） in the balanced inverter does not exist in the nMOSFET after the ion striking. The influence of the suhstrate process on the bipolar effect is also studied in the pMOSFET. We find that the bipolar effect can be effectively mitigated by a buried deep P＋-well layer and can be removed by a buried SO2 layer.展开更多
Single-event charge collection is controlled by drift, diffusion and the bipolar effect. Previous work has established that the bipolar effect is significant in the p-type metal-oxide-semiconductor field-effect transi...Single-event charge collection is controlled by drift, diffusion and the bipolar effect. Previous work has established that the bipolar effect is significant in the p-type metal-oxide-semiconductor field-effect transistor(PMOS) in 90 nm technology and above. However, the consequences of the bipolar effect on P-hit single-event transients have still not completely been characterized in 65 nm technology. In this paper, characterization of the consequences of the bipolar effect on P-hit single-event transients is performed by heavy ion experiments in both 65 nm twin-well and triple-well complementary metal-oxide-semiconductor(CMOS) technologies. Two inverter chains with clever layout structures are explored for the characterization. Ge(linear energy transfer(LET) = 37.4 Me V cm^2/mg) and Ti(LET = 22.2 Me V cm^2/mg) particles are also employed. The experimental results show that with Ge(Ti) exposure, the average pulse reduction is 49 ps(45 ps) in triple-well CMOS technology and 42 ps(32 ps) in twin-well CMOS technology when the bipolar effect is efficiently mitigated. This characterization will provide an important reference for radiation hardening integrated circuit design.展开更多
The n-type filled and doped skutterudites Ga_(x)Co_(4)Sb_(12.3) and Ga_(0.2)Co_(4)Sb_(11.3)Te composites with the welldistributed GaSb nanoinclusions are synthesized through the manipulating of metastable Ga fillers a...The n-type filled and doped skutterudites Ga_(x)Co_(4)Sb_(12.3) and Ga_(0.2)Co_(4)Sb_(11.3)Te composites with the welldistributed GaSb nanoinclusions are synthesized through the manipulating of metastable Ga fillers and enrichment of Sb by an in-situ method with a proper annealing procedure.Ga atoms can fill the icosahedron cages of skutterudite at high temperature,but at low temperature,they are driven out from the lattice voids and form the second phase of GaSb at grain boundaries.The presence of GaSb second phases reduces the thermal conductivity effectively.Te doping leads to a significant increase in carrier concentration of Ga_(0.2)Co_(4)Sb_(11.3)Te,thus largely suppresses the bipolar effect of Ga_(x)Co_(4)Sb_(12.3),resulting in a great enhancement in power factor.Moreover,Te doping induces mass and strain fluctuation,which decreases the lattice thermal conductivity further.Consequently,the maximum ZT is increased from 0.56 for Ga_(0.2)Co_(4)Sb_(12.3) at 573 K to 1.48 for Ga_(0.2)Co_(4)Sb_(11.3)Te at 873 K,which is advantageous to improve the thermoelectric conversion efficiency for commercial application.展开更多
This paper presents a theoretical study of the pulse-width effects on the damage process of a typical bipolar transistor caused by high power microwaves（HPMs） through the injection approach.The dependences of the mi...This paper presents a theoretical study of the pulse-width effects on the damage process of a typical bipolar transistor caused by high power microwaves（HPMs） through the injection approach.The dependences of the microwave damage power,P,and the absorbed energy,E,required to cause the device failure on the pulse width τ are obtained in the nanosecond region by utilizing the curve fitting method.A comparison of the microwave pulse damage data and the existing dc pulse damage data for the same transistor is carried out.By means of a two-dimensional simulator,ISE-TCAD,the internal damage processes of the device caused by microwave voltage signals and dc pulse voltage signals are analyzed comparatively.The simulation results suggest that the temperature-rising positions of the device induced by the microwaves in the negative and positive half periods are different,while only one hot spot exists under the injection of dc pulses.The results demonstrate that the microwave damage power threshold and the absorbed energy must exceed the dc pulse power threshold and the absorbed energy,respectively.The dc pulse damage data may be useful as a lower bound for microwave pulse damage data.展开更多
An analytical expression for the co/lector resistance of a novel vertical SiGe heterojunction bipolar transistor （HBT） on thin film silicon-on-insulator （SOI） is obtained with the substrate bias effects being cons...An analytical expression for the co/lector resistance of a novel vertical SiGe heterojunction bipolar transistor （HBT） on thin film silicon-on-insulator （SOI） is obtained with the substrate bias effects being considered. The resistance is found to decrease slowly and then quickly and to have kinks with the increase of the substrate-collector bias, which is quite different from that of a conventional bulk HBT. The model is consistent with the simulation result and the reported data and is useful to the frequency characteristic design of 0.13 μtm millimeter-wave SiGe SOI BiCMOS devices.展开更多
In this paper, we describe the saturation effect of a silicon germanium （SiGe） heterojunction bipolar transistor （HBT） fabricated on a thin silicon-on-insulator （SOI） with a step-by-step derivation of the model ...In this paper, we describe the saturation effect of a silicon germanium （SiGe） heterojunction bipolar transistor （HBT） fabricated on a thin silicon-on-insulator （SOI） with a step-by-step derivation of the model formulation. The collector injection width, the internal base-collector bias, and the hole density at the base-collector junction interface are analysed by considering the unique features of the internal and the external parts of the collector, as they are different from those of a bulk counterpart.展开更多
Silicon germanium （SiGe） heterojunction bipolar transistor （HBT） on thin silicon-on-insulator （SOI） has recently been demonstrated and integrated into the latest SOI BiCMOS technology. The Early effect of the SO...Silicon germanium （SiGe） heterojunction bipolar transistor （HBT） on thin silicon-on-insulator （SOI） has recently been demonstrated and integrated into the latest SOI BiCMOS technology. The Early effect of the SOI SiGe HBT is analysed considering vertical and horizontal collector depletion, which is different from that of a bulk counterpart. A new compact formula of the Early voltage is presented and validated by an ISE TCAD simulation. The Early voltage shows a kink with the increase of the reverse base-collector bias. Large differences are observed between SOI devices and their bulk counterparts. The presented Early effect model can be employed for a fast evaluation of the Early voltage and is useful to the design, the simulation and the fabrication of high performance SOI SiCe devices and circuits.展开更多
The radiation effects of the metal-oxide-semiconductor （MOS） and the bipolar devices are characterised using 8 MeV protons, 60 MeV Br ions and 1 MeV electrons. Key parameters are measured in-situ and compared for th...The radiation effects of the metal-oxide-semiconductor （MOS） and the bipolar devices are characterised using 8 MeV protons, 60 MeV Br ions and 1 MeV electrons. Key parameters are measured in-situ and compared for the devices. The ionising and nonionising energy losses of incident particles are calculated using the Geant4 and the stopping and range of ions in matter code. The results of the experiment and energy loss calculation for different particles show that different incident particles may give different contributions to MOS and bipolar devices. The irradiation particles, which cause a larger displacement dose within the same chip depth of bipolar devices at a given total dose, would generate more severe damage to the voltage parameters of the bipolar devices. On the contrary, the irradiation particles, which cause larger ionising damage in the gate oxide, would generate more severe damage to MOS devices. In this investigation, we attempt to analyse the sensitivity to radiation damage of the different parameter of the MOS and bipolar devices by comparing the irradiation experimental data and the calculated results using Geant4 and SRIM code.展开更多
The contribution of parasitic bipolar amplification to SETs is experimentally verified using two P-hit target chains in the normal layout and in the special layout. For PMOSs in the normal layout, the single-event cha...The contribution of parasitic bipolar amplification to SETs is experimentally verified using two P-hit target chains in the normal layout and in the special layout. For PMOSs in the normal layout, the single-event charge collection is composed of diffusion, drift, and the parasitic bipolar effect, while for PMOSs in the special layout, the parasitic bipolar junction transistor cannot turn on. Heavy ion experimental results show that PMOSs without parasitic bipolar amplification have a 21.4% decrease in the average SET pulse width and roughly a 40.2% reduction in the SET cross-section.展开更多
目的:分析哌罗匹隆联合拉莫三嗪治疗双相情感障碍(Bipolar disorder,BPD)抑郁发作患者的效果及安全性。方法:回顾性分析2021年1月至2023年11月本院收治的82例BPD抑郁发作患者的临床资料。其中对照组(n=40)采用拉莫三嗪口服治疗,首次剂量...目的:分析哌罗匹隆联合拉莫三嗪治疗双相情感障碍(Bipolar disorder,BPD)抑郁发作患者的效果及安全性。方法:回顾性分析2021年1月至2023年11月本院收治的82例BPD抑郁发作患者的临床资料。其中对照组(n=40)采用拉莫三嗪口服治疗,首次剂量25-50 mg·d^(-1),2次·d^(-1),观察组(n=42)基于对照组联用哌罗匹隆初始口服治疗,4 mg·d^(-1),1次·d^(-1),两组持续用药8 w。分析对比两组临床疗效,于治疗前后分别采用汉密尔顿抑郁量表-17项(Hamilton depression scale,HAMD-17)、临床总体印象⁃双相情感障碍病情程度量表(Clinical global impression scale-bipolar disorder,CGI-S-BP)、重复性成套神经心理状态测验(Repeatable battery for the assessment of neuropsychological status,RBANS)和世界卫生组织生存质量测定简表(The world health organization quality of life,WHOQOL-BREF)评估患者抑郁程度、BPD病情程度、心理认知和生存质量,同时采用酶联免疫吸附法检测5羟色胺(5-Hydroxytryptamine,5-HT)、谷氨酸(Glutamic acid,Glu)、血清γ氨基丁酸(γ-aminobutyric acid,GABA)水平,记录不良反应发生率。结果:观察组治疗总有效率显著高于对照组(P<0.05);与治疗前相比,两组治疗4 w、8 w后HAMD-17、CGI-S-BP评分均降低,RBANS、WHOQOL-BREF评分均提高,且观察组变化幅度均显著大于对照组(P<0.05);与对照组相比,观察组治疗4 w、8 w后的GABA、5-HT水平均显著升高,Glu水平显著降低(P<0.05);两组不良反应总发生率无显著差异(P>0.05)。结论:哌罗匹隆联合拉莫三嗪可有效改善BPD抑郁发作患者情绪,减轻抑郁症状,提高生存质量,且具有一定安全性。展开更多
基金The work is supported by the National Natural Science Foundation of China(No.52071218)Shenzhen Science and Technology Innovation Commission(Nos.20200731215211001,20200814110413001)Guangdong Basic and Applied Basic Research Foundation(No.2022A1515012492).The authors also appreciate the Instrumental Analysis Center of Shenzhen University.
文摘To date,the benchmark Bi_(2)Te_(3)-based alloys are still the only commercial material system used for ther-moelectric solid-state refrigeration.Nonetheless,the conspicuous performance imbalance between the p-type Bi_(2-x)Sb_(x)Te_(3)and n-type Bi_(2)Te_(3-x)Se_(x) legs has become a major obstacle for the improvement of cooling devices to achieve higher efficiency.In our previous study,novel n-type Bi_(2-x)Sb_(x)Te_(3)alloy has been pro-posed via manipulating donor-like effect as an alternative to mainstream n-type Bi_(2)Te_(3-x)Se_(x).However,the narrow bandgap of Bi_(2-x)Sb_(x)Te_(3)provoked severe bipolar effect that constrained the further improvement of zT near room temperature.Herein,we have implemented band gap engineering in n-type Bi_(1.5)Sb_(0.5)Te_(3)by employing isovalent Se substitution to inhibit the undesired intrinsic excitation and achieve the dis-tinguished room-temperature zT.First,the preferential occupancy of Se at Te^(2)site appropriately enlarges the band gap,thereby concurrently improving the Seebeck coefficient and depressing the bipolar thermal conductivity.In addition,the Se alloying mildly suppresses the compensation mechanism and essentially preserves the already optimized carrier concentration,which maintains the peak zT near room tempera-ture.Moreover,the large strain field and mass fluctuation generated by Se alloying leads to the remark-able reduction of lattice thermal conductivity.Accordingly,the zT value of Bi_(1.5)Sb_(0.5)Te_(2.8)Se_(0.2)reaches 1.0 at 300 K and peaks 1.1 at 360 K,which surpasses that of most well-known room-temperature n-type thermoelectric materials.These results pave the way for n-type Bi_(2-x)Sb_(x)Te_(3)alloys to become a new and promising top candidate for large-scale solid-state cooling applications.
基金Project supported by the Key Program of the National Natural Science Foundation of China(Grant No.60836004)the National Natural Science Foundation of China(Grant Nos.61006070 and 61076025)
文摘In this paper, a new method is proposed to study the mechanism of charge collection in single event transient （SET） production in 90 nm bulk complementary metal oxide semiconductor （CMOS） technology. We find that different from the case in the pMOSFET, the parasitic bipolar amplification effect （bipolar effect） in the balanced inverter does not exist in the nMOSFET after the ion striking. The influence of the suhstrate process on the bipolar effect is also studied in the pMOSFET. We find that the bipolar effect can be effectively mitigated by a buried deep P＋-well layer and can be removed by a buried SO2 layer.
基金supported by the National Natural Science Foundation of China(Grant No.61504169)the Preliminary Research Program of National University of Defense Technology of China(Grant No.0100066314001)
文摘Single-event charge collection is controlled by drift, diffusion and the bipolar effect. Previous work has established that the bipolar effect is significant in the p-type metal-oxide-semiconductor field-effect transistor(PMOS) in 90 nm technology and above. However, the consequences of the bipolar effect on P-hit single-event transients have still not completely been characterized in 65 nm technology. In this paper, characterization of the consequences of the bipolar effect on P-hit single-event transients is performed by heavy ion experiments in both 65 nm twin-well and triple-well complementary metal-oxide-semiconductor(CMOS) technologies. Two inverter chains with clever layout structures are explored for the characterization. Ge(linear energy transfer(LET) = 37.4 Me V cm^2/mg) and Ti(LET = 22.2 Me V cm^2/mg) particles are also employed. The experimental results show that with Ge(Ti) exposure, the average pulse reduction is 49 ps(45 ps) in triple-well CMOS technology and 42 ps(32 ps) in twin-well CMOS technology when the bipolar effect is efficiently mitigated. This characterization will provide an important reference for radiation hardening integrated circuit design.
基金supported by the National Natural Science Foundation of China(Nos.61604031,51672037 and 61727818)the subproject of the National Key and Development Program of China(No.2017YFC0602102)the Department of Science and Technology of Sichuan Province(No.2019YFH0009).
文摘The n-type filled and doped skutterudites Ga_(x)Co_(4)Sb_(12.3) and Ga_(0.2)Co_(4)Sb_(11.3)Te composites with the welldistributed GaSb nanoinclusions are synthesized through the manipulating of metastable Ga fillers and enrichment of Sb by an in-situ method with a proper annealing procedure.Ga atoms can fill the icosahedron cages of skutterudite at high temperature,but at low temperature,they are driven out from the lattice voids and form the second phase of GaSb at grain boundaries.The presence of GaSb second phases reduces the thermal conductivity effectively.Te doping leads to a significant increase in carrier concentration of Ga_(0.2)Co_(4)Sb_(11.3)Te,thus largely suppresses the bipolar effect of Ga_(x)Co_(4)Sb_(12.3),resulting in a great enhancement in power factor.Moreover,Te doping induces mass and strain fluctuation,which decreases the lattice thermal conductivity further.Consequently,the maximum ZT is increased from 0.56 for Ga_(0.2)Co_(4)Sb_(12.3) at 573 K to 1.48 for Ga_(0.2)Co_(4)Sb_(11.3)Te at 873 K,which is advantageous to improve the thermoelectric conversion efficiency for commercial application.
基金Project supported by the National Natural Science Foundation of China (Grant No. 60776034)
文摘This paper presents a theoretical study of the pulse-width effects on the damage process of a typical bipolar transistor caused by high power microwaves（HPMs） through the injection approach.The dependences of the microwave damage power,P,and the absorbed energy,E,required to cause the device failure on the pulse width τ are obtained in the nanosecond region by utilizing the curve fitting method.A comparison of the microwave pulse damage data and the existing dc pulse damage data for the same transistor is carried out.By means of a two-dimensional simulator,ISE-TCAD,the internal damage processes of the device caused by microwave voltage signals and dc pulse voltage signals are analyzed comparatively.The simulation results suggest that the temperature-rising positions of the device induced by the microwaves in the negative and positive half periods are different,while only one hot spot exists under the injection of dc pulses.The results demonstrate that the microwave damage power threshold and the absorbed energy must exceed the dc pulse power threshold and the absorbed energy,respectively.The dc pulse damage data may be useful as a lower bound for microwave pulse damage data.
基金Project supported by National Ministries and Commissions(Grant Nos.51308040203 and 6139801)the Fundamental Research Funds for the Central Universities,China(Grant Nos.72105499 and 72104089)the Natural Science Basic Research Plan in Shaanxi Province of China(Grant No.2010JQ8008)
文摘An analytical expression for the co/lector resistance of a novel vertical SiGe heterojunction bipolar transistor （HBT） on thin film silicon-on-insulator （SOI） is obtained with the substrate bias effects being considered. The resistance is found to decrease slowly and then quickly and to have kinks with the increase of the substrate-collector bias, which is quite different from that of a conventional bulk HBT. The model is consistent with the simulation result and the reported data and is useful to the frequency characteristic design of 0.13 μtm millimeter-wave SiGe SOI BiCMOS devices.
基金Project supported by the National Ministries and Commissions,China (Grant Nos.51308040203 and 6139801)the Fundamental Research Funds for the Central Universities,China (Grant Nos.72105499 and 72104089)the Basic Natural Science Research Program in Shaanxi Province,China (Grant No.2010JQ8008)
文摘In this paper, we describe the saturation effect of a silicon germanium （SiGe） heterojunction bipolar transistor （HBT） fabricated on a thin silicon-on-insulator （SOI） with a step-by-step derivation of the model formulation. The collector injection width, the internal base-collector bias, and the hole density at the base-collector junction interface are analysed by considering the unique features of the internal and the external parts of the collector, as they are different from those of a bulk counterpart.
基金Project supported by the National Ministries and Commissions (Grant Nos. 51308040203 and 6139801)the Fundamental Research Funds for the Central Universities of China (Grant Nos. 72105499 and 72104089)the Natural Science Basic Research Plan in Shaanxi Province of China (Grant No. 2010JQ8008)
文摘Silicon germanium （SiGe） heterojunction bipolar transistor （HBT） on thin silicon-on-insulator （SOI） has recently been demonstrated and integrated into the latest SOI BiCMOS technology. The Early effect of the SOI SiGe HBT is analysed considering vertical and horizontal collector depletion, which is different from that of a bulk counterpart. A new compact formula of the Early voltage is presented and validated by an ISE TCAD simulation. The Early voltage shows a kink with the increase of the reverse base-collector bias. Large differences are observed between SOI devices and their bulk counterparts. The presented Early effect model can be employed for a fast evaluation of the Early voltage and is useful to the design, the simulation and the fabrication of high performance SOI SiCe devices and circuits.
基金Project supported by the National Basis Research Program of China (Grant No. 61343)
文摘The radiation effects of the metal-oxide-semiconductor （MOS） and the bipolar devices are characterised using 8 MeV protons, 60 MeV Br ions and 1 MeV electrons. Key parameters are measured in-situ and compared for the devices. The ionising and nonionising energy losses of incident particles are calculated using the Geant4 and the stopping and range of ions in matter code. The results of the experiment and energy loss calculation for different particles show that different incident particles may give different contributions to MOS and bipolar devices. The irradiation particles, which cause a larger displacement dose within the same chip depth of bipolar devices at a given total dose, would generate more severe damage to the voltage parameters of the bipolar devices. On the contrary, the irradiation particles, which cause larger ionising damage in the gate oxide, would generate more severe damage to MOS devices. In this investigation, we attempt to analyse the sensitivity to radiation damage of the different parameter of the MOS and bipolar devices by comparing the irradiation experimental data and the calculated results using Geant4 and SRIM code.
基金supported by the National Natural Science Foundation of China(Grant No.61376109)
文摘The contribution of parasitic bipolar amplification to SETs is experimentally verified using two P-hit target chains in the normal layout and in the special layout. For PMOSs in the normal layout, the single-event charge collection is composed of diffusion, drift, and the parasitic bipolar effect, while for PMOSs in the special layout, the parasitic bipolar junction transistor cannot turn on. Heavy ion experimental results show that PMOSs without parasitic bipolar amplification have a 21.4% decrease in the average SET pulse width and roughly a 40.2% reduction in the SET cross-section.
文摘目的:分析哌罗匹隆联合拉莫三嗪治疗双相情感障碍(Bipolar disorder,BPD)抑郁发作患者的效果及安全性。方法:回顾性分析2021年1月至2023年11月本院收治的82例BPD抑郁发作患者的临床资料。其中对照组(n=40)采用拉莫三嗪口服治疗,首次剂量25-50 mg·d^(-1),2次·d^(-1),观察组(n=42)基于对照组联用哌罗匹隆初始口服治疗,4 mg·d^(-1),1次·d^(-1),两组持续用药8 w。分析对比两组临床疗效,于治疗前后分别采用汉密尔顿抑郁量表-17项(Hamilton depression scale,HAMD-17)、临床总体印象⁃双相情感障碍病情程度量表(Clinical global impression scale-bipolar disorder,CGI-S-BP)、重复性成套神经心理状态测验(Repeatable battery for the assessment of neuropsychological status,RBANS)和世界卫生组织生存质量测定简表(The world health organization quality of life,WHOQOL-BREF)评估患者抑郁程度、BPD病情程度、心理认知和生存质量,同时采用酶联免疫吸附法检测5羟色胺(5-Hydroxytryptamine,5-HT)、谷氨酸(Glutamic acid,Glu)、血清γ氨基丁酸(γ-aminobutyric acid,GABA)水平,记录不良反应发生率。结果:观察组治疗总有效率显著高于对照组(P<0.05);与治疗前相比,两组治疗4 w、8 w后HAMD-17、CGI-S-BP评分均降低,RBANS、WHOQOL-BREF评分均提高,且观察组变化幅度均显著大于对照组(P<0.05);与对照组相比,观察组治疗4 w、8 w后的GABA、5-HT水平均显著升高,Glu水平显著降低(P<0.05);两组不良反应总发生率无显著差异(P>0.05)。结论:哌罗匹隆联合拉莫三嗪可有效改善BPD抑郁发作患者情绪,减轻抑郁症状,提高生存质量,且具有一定安全性。
