silicon期刊

silicon期刊

导读

背景

光子学（photonics）是研究作为信息和能量载体的光子的行为及其应用的学科。光子学及其发展的相关技术即光子技术，具有丰富的内涵和广阔的应用前景。如果你使用智能手机、笔记本电脑、平板电脑，那么就有望从光子学的研究中获益。

创新

近日，美国特拉华大学电气与计算机工程系助理教授 Tingyi Gu 领导的一支团队正在开发光子器件方面的前沿技术，该技术可以使得器件之间以及使用者之间的通信速度更快。

最近，该研究小组设计出一种“硅-石墨烯”器件，它能以亚太赫兹的带宽，在一皮秒之内发射无线电波。这样不仅可携带更多信息，而且速度也更快。他们的研究近期发表在《美国化学会应用电子材料（ACS Applied Electronic Materials）》期刊上。

论文第一作者、研究生 Dun Mao 表示：“在这项研究中，我们仔细研究了用于未来光电子应用的集成石墨烯的硅光子器件的带宽限制。”

技术

硅是大自然产生的一种非常富足的材料，通常作为电子器件中的半导体使用。然而，研究人员们已经耗尽了仅由硅制成的半导体器件的潜能。这些设备受制于硅的载流子迁移率（电荷通过材料的速度）以及间接带隙（限制了释放和吸收光线的能力）。

现在，Gu 的团队将硅与一种具有更多有益特性的材料（二维材料石墨烯）相结合。二维材料以只有一层原子而得名。与硅相比，石墨烯具有更好的载流子迁移率以及直接带隙，使得电子传输得更快，并且电气和光学特性更好。通过将硅与石墨烯相结合，科学家们将可以继续利用已经在硅器件中使用的技术，硅与石墨烯的结合使运行速度变得更快。博士生 Thomas Kananen 表示：“通过研究材料的特性，我们能否比现在做更多的事情？这就是我们想要搞清楚的。”

为了将硅与石墨烯相结合，团队采用了一种他们正在开发的方法。一篇发表在《npj 2D Materials and Application》期刊上的论文描述了这种方法。团队将石墨烯放置到一个特殊的地方，即所谓的“p-i-n结”。它是材料之间的一种接口。通过将石墨烯放置在“p-i-n 结”上，团队以一种可以提升响应率和器件速度的方法优化了这个结构。

这个方法很健壮，而且便于其他研究人员采用。这一工艺产生在12英寸的超薄材料晶圆上，并利用了小于一毫米的元件。某些元件是在商业制造厂生产。其他的工作在特拉华大学的纳米制造设施进行，材料科学与工程系副教授 Matt Doty 是该设施的主任。

Doty 表示：“特拉华大学纳米制造设施（UNDF）是一个员工支持的工厂，它使用户可在7纳米的长度级别制造设备，约为人类发丝直径的万分之一。UNDF成立于2016年，为从光电子学到生物医学再到植物科学的一系列领域带来了新的研究方向。”

价值

硅与石墨烯结合之后，可作为光电探测器使用，可以感知光线，并制造电流，并且比现有方案的带宽更大和响应时间更少。所有这些研究意味着未来将带来更便宜、更快速的无线设备。博士后研究员、发表在《npj 2D Materials and Application》期刊上的论文第一作者 Tiantian Li 表示：“它可以使得网络更强、更好、更便宜。这是光子学的关键点。”

现在，团队正在思考拓展这种材料的应用途径。Gu 表示：“我们正在寻找更多的基于类似结构的元件。”

关键字

参考资料

【1】

【2】Dun Mao, Thomas Kananen, Tiantian Li, Anishkumar Soman, Jeffrey Sinsky, Nicholas Petrone, James Hone, Po Dong, Tingyi Gu. Bandwidth Limitation of Directly Contacted Graphene–Silicon Optoelectronics. ACS Applied Electronic Materials, 2019; 1 (2): 172 DOI: 10.1021/acsaelm.8b00015

中国教育文荟杂志 一级学术性中文核心期刊

《中国教育文荟》杂志是综合性教育科研刊物，中国教育科研研究会主办，一级学术性中文核心期刊，国家二级刊物。栏目设置：学科教研、课题研究、高等教育、师德师表、职业教育与教学、教育改革、教学管理、办学模式探索、德育研究、教学技能、科学研究与技术开发、教海探航、素质与创新教育、国外教育、科技论坛、农村教育、教学艺术、评价园地、课改实践、基础教育等。

“纵观全局，分布实施”的方式在网络管理系统配置中更加适用。

从宏观层面上，首先应确定网络管理的范围和管理的程度，其次要评估网络的规模和管理的数据量，再次需确定网络的结构特点。

一般地，如果高校规模较小，可以选择集中式的网络管理系统，更易于管理。如果高校规模较大，网络上所有网管轮询(Polling)和网管信息量增大，此时集中式网管中心可能成为网管系统的瓶颈,并且网络管理信息流导致网络可用带宽减少，这时应采用分布式的网络管理模式,将网络管理的任务分散在不同的网管中心完成。究竟采用哪种管理模式取决于校园网具体的规模、结构和需求。

从微观层面上，要选择合适的网管软件。网管软件是网络管理员的眼睛、耳朵、手和脚，只有充分调动起各个“器官”，才能有效地发挥出网管的效能。在选择网管软件时，应该考虑软件对以下几个需求的满足。1.校园网需要哪些管理功能；2.网络管理软件支持哪些标准。至少应支持SNMP和RMON；3.支持各种硬件、软件的范围。一般应可支持Sun、IBM、HP、NT、AT&T(NCR)、DEC、Linux、DataGeneral、SiliconGraphics、Motorola、Sequent、Pyramid、SCOUnix、Unisys、Windows3.x/95/NT、OS/2和Novell；4.可管理性如何；5.可扩展性如何。
“纵观全局，分布实施”的方式在网络管理系统配置中更加适用。

从宏观层面上，首先应确定网络管理的范围和管理的程度，其次要评估网络的规模和管理的数据量，再次需确定网络的结构特点。

一般地，如果高校规模较小，可以选择集中式的网络管理系统，更易于管理。如果高校规模较大，网络上所有网管轮询(Polling)和网管信息量增大，此时集中式网管中心可能成为网管系统的瓶颈,并且网络管理信息流导致网络可用带宽减少，这时应采用分布式的网络管理模式,将网络管理的任务分散在不同的网管中心完成。究竟采用哪种管理模式取决于校园网具体的规模、结构和需求。

从微观层面上，要选择合适的网管软件。网管软件是网络管理员的眼睛、耳朵、手和脚，只有充分调动起各个“器官”，才能有效地发挥出网管的效能。在选择网管软件时，应该考虑软件对以下几个需求的满足。1.校园网需要哪些管理功能；2.网络管理软件支持哪些标准。至少应支持SNMP和RMON；3.支持各种硬件、软件的范围。一般应可支持Sun、IBM、HP、NT、AT&T(NCR)、DEC、Linux、DataGeneral、SiliconGraphics、Motorola、Sequent、Pyramid、SCOUnix、Unisys、Windows3.x/95/NT、OS/2和Novell；4.可管理性如何；5.可扩展性如何。
“纵观全局，分布实施”的方式在网络管理系统配置中更加适用。

从宏观层面上，首先应确定网络管理的范围和管理的程度，其次要评估网络的规模和管理的数据量，再次需确定网络的结构特点。

一般地，如果高校规模较小，可以选择集中式的网络管理系统，更易于管理。如果高校规模较大，网络上所有网管轮询(Polling)和网管信息量增大，此时集中式网管中心可能成为网管系统的瓶颈,并且网络管理信息流导致网络可用带宽减少，这时应采用分布式的网络管理模式,将网络管理的任务分散在不同的网管中心完成。究竟采用哪种管理模式取决于校园网具体的规模、结构和需求。

从微观层面上，要选择合适的网管软件。网管软件是网络管理员的眼睛、耳朵、手和脚，只有充分调动起各个“器官”，才能有效地发挥出网管的效能。在选择网管软件时，应该考虑软件对以下几个需求的满足。1.校园网需要哪些管理功能；2.网络管理软件支持哪些标准。至少应支持SNMP和RMON；3.支持各种硬件、软件的范围。一般应可支持Sun、IBM、HP、NT、AT&T(NCR)、DEC、Linux、DataGeneral、SiliconGraphics、Motorola、Sequent、Pyramid、SCOUnix、Unisys、Windows3.x/95/NT、OS/2和Novell；4.可管理性如何；5.可扩展性如何。

设备的安全是网络运行安全的首要环节。相关人士表示，设备管理要统筹规划，要避免大面积出现老化的问题，这就要求网络中心避免一次性购买大量同种设备。因为设备的使用年限几乎差不多，也就是说，在大面积购买的情况下，到一定的时间后，很多设备几乎都会在同一个时间段内出现问题，导致网络不能正常运行，因此学校在采购时应该考虑此因素，免得到时候出现“按下葫芦又起瓢”的无奈状况。

另外，在设备安全方面需要注意的是，一旦发现设备的漏洞，应及时责成厂商作出修改。厂商一般在了解自身漏洞的当即不会采取行动，因为更新一个漏洞的成本很高，只有在漏洞积累到一定量的时候，厂商才会一次性更新，但是这样做显然是把风险留给了用户。在厂商更新之前，一旦此漏洞被利用，那么对用户来说非常危险。因此，用户在获悉漏洞情况之后，应尽量促成厂商的解决。

第二，实施用户管理策略。目前，清华大学正在尝试将信任机制引入网络管理中。他们对用户行为进行分析，以分析所得数据为基础对用户进行分级管理。相关人士表示，客户端用户行为数据的收集对于改善网络的可用性至关重要，非常有助于进一步改善网络的可用性。相关老师认为，在高校这样“内患”较多的局域网内，对用户行为分析很有必要。只是也存在一个问题，学生在4年以后离校，这意味着这些数据对学校而言已经失去意义。不过行为分析具有一定的威慑力，在学生在校期间，行为分析可起到一定作用，使得网络中的一些不良行为发生的概率降低，从而保障网络的正常运行。

第三，实施网管员自身提升策略。不断提升网络管理人员的能力是网络管理的根本之道，同时还需将管理规范化。一般来说，网络管理与维护人员比较少，日常处理的事务却非常多，他们需要在网络、链路和系统运行出现问题时能够有自动化、规范化的处理程序，以提高工作效率。建立规范事件处理程序的另一个好处是将网管人员长期积累的知识和工作经验系统化，达到快速定位故障的目的。

求几篇关于变压器故障预测，故障检测、检测手段的英文论文或期刊，作者最好是美国的邮箱834409809@

Testing the "System on a Chip"
Much has been written about the concept of a "system on a chip," the ever-increasing integration of logic and analog functions on one silicon die or chip. This paradigm is about to change. The results of work by universities, national labs, and companies such as Motorola, Inc., are paving the way for a true system on a chip, or SOC. These new SOCs will not only analyze data, but will measure, analyze, and react to their environment.

The integration of power and analog elements with a CMOS microcontroller unit (MCU) has been possible for several years. Products have been introduced such as an integrated 68HC05 motor controller with integral power devices in an H-bridge configuration (1990). In 1993, a product called a System Chip MCU was introduced that provided a Society of Automotive Engineers J1850 interface, including the physical layer. This chip could withstand 40 V, based on the combination of power and analog capability with the MCU. However, the system input was not included in previous monolithic designs.

What is the most recent development that promises to truly enable a system on a chip? It is the ability to combine CMOS and MEMS (microelectromechanical systems) structures into one process flow. Photo 1 illustrates a 68HC05 microcontroller with a 100 kPa pressure sensor integrated onto a single silicon die. A likely application is a side air bag sensor.

A pressure sensor, inside the door panel of a car, could detect the change in pressure when the panel crumples under an impact. The ability to program the onchip microcontroller will enable the auto manufacturer to embed the control algorithm inside the chip. To complete an entire system, only a mechanism for actuating the air bag need be added. This actuation capability could be yet another step in the continuous integration of silicon and electronics/electromechanical systems. This platform provides a first step in the integration of electronics with electromechanical structures and at the same time raises several issues that must be resolved before a low-cost, high-quality product can be mass produced. One of these issues is that of testability.

Typical logic circuits have many years of accumulated test data that can be used as a foundation for building the next generation of product. With sensors, however, very little previous technology can be reused. The reasons are the relative infancy of sensor technology and the uniqueness of each type of sensor. For example, the technology used to measure pressure (a thin diaphragm with integral strain gauge) is much different from that used for measuring acceleration (a proof mass forming a moving capacitor). The testing technology is different as well. Pressure measurements require a pressure source to be connected to the sensor; acceleration or shock detection requires shaking the device at some known frequency and force.

System Configuration
To develop a proof-of-concept vehicle (see Figure 1), a 100 kPa pressure sensor was integrated onto Motorola's standard 8-bit 68HC05 microcontroller core along with the associated analog circuitry [1]. To this basic core was added analog circuitry for signal conditioning, a voltage and current regulator, and 10-bit A/D and 8-bit D/A converters. A temperature sensor was also incorporated into the design for compensation purposes.
The pressure transducer is temperature dependent and has an inherent nonlinearity. To increase the accuracy of the system, a calibration or conditioning algorithm must be programmed into the microcontroller.

The pressure transducer's output is conditioned by a variable gain and input offset amplifier that is controlled by the program stored in the MCU. The A/D converter is used to read the temperature sensor's and the pressure transducer's outputs. The band gap voltage regulator supplies a constant voltage for the pressure sensor, amplifier, and A/D converter. The band gap current regulator provides a constant current source for the temperature sensor.

Calibration Method
The MCU calibrates and compensates the pressure sensor's nonlinearity and temperature drift. To provide the maximum accuracy, an A/D input resolution of 10 bits was chosen and the calculation resolution was set at 16 bits, fixed point. To calibrate span and offset and compensate the nonlinearity of the sensor output, calibration software performs a second-order polynomial correction of sensor output described as:
Vout = c0 + c1Vp + c2Vp2 (1)
Cp = (c0, c1, c2 ) (2)

where:

Vout = calibrated output
Vp = uncompensated pressure sensor output

To compensate the temperature dependency of Cp, calibration software is used to calculate Cp using a second-order polynomial fitting equation to temperature:

c0 = c00 + c01Vt + c02 Vt2 (3)
c1 = c10 + c11Vt + c12 Vt2 (4)
c2 = c20 + c21Vt + c22Vt2 (5)
(6)

where:

Vt = temperature sensor output

The Cts are read during the calibration procedure and stored in EPROM. The MCU calculates Cp from the temperature sensor output, Vt, and Ct. Cp is then used to calculate the calibrated pressure sensor output using the pressure transducer's output, Vp.

Calibration Procedure
The calibration system first adjusts the gain and offset of the amplifier to use the full A/D range. Then the characteristics of the uncompensated pressure sensor output are examined over several temperature points. At each temperature, a second-order polynomial described in Equation 1 is obtained by least square fitting and the coefficient set, Cp, is determined. After completing the calculation of Cp over all temperature points, Ct is determined by the least square fitting of Equations 3, 4, and 5 to determine Cp over the temperature points. At present, at least three separate temperature sampling points are required to complete the fitting calculation.

Figure 2. The uncompensated output of the sensor-based system on a chip is plotted at four different temperatures.

Characteristics
Figure 2 shows the uncompensated sensor output characteristics over various temperatures after adjusting gain and offset. Based on these data, the coefficients for calibration were calculated and written into the onchip EPROM by the calibration system. The compensation value was rounded off to 8 bits. Figure 3 shows the calibrated and compensated output of the integrated MCU. Figure 4 shows the error from expected values. Since 1 bit is 0.4% error, the result indicates the error is within 0.4% of full-scale output.

Figure 3. Compensated output of the system on a chip is improved through testing and calibration at three temperatures.

Test Issues
Several issues are raised by this initial work, including the different types of testing required, unique test equipment, and the need for multipass testing. To make a low-cost integrated solution possible, these concerns must be addressed.

The integration of a physical measurement function onto the already complex mixed-mode analog-digital chip raises the need for an additional type of testing. The physical medium being tested must be applied to the device and the response must be measured. Measuring the response to a physical stimulus is not a
Figure 4. Bit error in the compensated output is within 1 bit at both 30°C and 85°C

standard test for the semiconductor industry, especially under multiple temperatures. Standard equipment can test the digital and analog portions of the chip, but the application of a physical stimulus and the procedure of heating and cooling the device under test rapidly and accurately drive the need for a modified and unique tester. These testers are one of a kind and are not available as a standard. The tester therefore represents a large part of the final unit's cost.

Not only are the testers expensive, but the throughput is limited. This raises the cost of each part because of the increased depreciation costs allocated to each device. The cost is further increased by the need for multipass testing. Remember that each part is first tested, using at least three different temperatures, to determine the transducer's output characteristics over temperature. Then these values are used to derive the compensation algorithm, which is loaded into the onchip EPROM. To complete the cycle, the device is once again tested over temperature to prove accuracy. Hence, not only is a special tester required, but it becomes a bottleneck since it must be used twice to complete each device—once to measure the characteristics and a second time to verify the result.

Future Directions
Finding ways to reduce the cost of testing is one of the keys to making a low-cost integrated sensor and MCU a reality. Ideas that could prove promising include:
Thoroughly characterizing the design
Limiting the operating temperature
Limiting the accuracy
Programming the MCU to take data during testing
Loading the test and compensation algorithm into the MCU before testing
Since this is a first proof-of-concept device, further characterization could provide a way to limit the number of temperatures required for compensations. Limiting the operating temperature range could also reduce the number of temperatures required for compensation testing. Data shown in Figure 3 indicate a 5% accuracy from 5°C to 25°C. Another potential cost reduction step would be to use the MCU's programmability for data logging during test. By storing the compensation program in the onchip EPROM prior to test, and then logging the uncompensated output into the EPROM during test, it might be possible to develop an algorithm for a one-pass test over temperature.

Without a breakthrough in lowering the cost of testing this new integrated sensor and MCU, the system designer may be limited to the continued use of the present day solution—separate MCU and sensor.
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All the DS18B20 sensors, used for the multipoint test temperature, are connected with MCU on one of IO bus, and temperature data are collected by turns. If the system has a large amount of sensors, the time of MCU used in processing the temperature data is obviously prolonged, so the cycle of alternate test gets longer. In this paper, a new method that DS18B20 are rationally grouped is presented, and some measures are taken in software; as a result, the speed of alternate test advances distinctly.