使用AC Hall效应方法进行低移动材料欧洲杯足球竞彩

使用直流磁场对大厅效应的测量是一种可靠的技术，用于表征半导体材料的电子传输性能。欧洲杯足球竞彩

霍尔的效果专门用于确定载体浓度，载体类型以及材料的霍尔系数和迁移率。欧洲杯足球竞彩目前，只有很少的DC现场技术来表征迁移率低的材料，包括用于太阳能电池技术，热电技术和有机电子产品的材料。欧洲杯足球竞彩

目前，使用AC磁场而不是常规DC的HALL效应测量方法正在吸引越来越多的兴趣。该方法是由Toyo在日本设计的，并已成功使用了15年以上，为研究低流动性材料的性质的研究人员提供了更好的解决方案。欧洲杯足球竞彩该技术可以衡量低至10的迁移率^-3centimeters squared per volt per second (cm²/（vs）），而直流现场技术通常仅限于衡量约1厘米的迁移率²/（VS）在传统实验室电磁体产生的直流磁场中。

DC现场大厅效应测量基础知识

这Hall’s effect occurs when a voltage is produced in a direction transverse to an electric current in a conductor due to the application of a magnetic field perpendicular to the current (Fig. 1). The ratio of the induced electric field to the product of the applied current density and the magnetic field divided by the sample thickness is termed as the Hall coefficient.

这Hall coefficient characterizes the material the conductor is made of, since its value may vary based on the type, number and properties of the charge carriers that constitute the current. Measuring the Hall effect over a range of temperatures offers insight into the material charge transport mechanisms. The measurement of the Hall effect in material samples produced using different methods, can be used to evaluate the performances of the material in an electronic device and help optimizing the production techniques. The Hall mobility is one of the most significant electronic properties of a material.

Figure 1.大厅效应的插图

霍尔效应和电阻率测量的常规方法使用直流磁场。霍尔电压与施加的磁场，电流，材料的霍尔系数和材料样品厚度的倒数成正比。理想情况下，未应用场时测得的霍尔电压为零。但是，测得的电压通常包括由未对准和热电电压引起的贡献。

未对准电压与材料和电流的电阻率成正比，并取决于样品几何形状。热电电压来自两种不同材料之间的接触，尽管它取决于热梯度的存在，但不取决于电流。欧洲杯足球竞彩在DC场测量中，使用场反转来消除未对准电压，并且电流逆转用于卸下热电电压。

DC方法的缺点

DC方法的一些主要缺点如下：

• 在低迁移率材料中，与霍尔电压相比欧洲杯足球竞彩，未对准和热电电压可能很大，霍尔电压限制了用于测量电压的直流电压表的动态范围。
• 此外，未对准和热电电压可能会随着时间的推移而变化，从而在使用场反转测量的霍尔电压中产生系统误差。这些效果使得很难从测量的电压中精确提取小厅电压，从而又限制了测量霍尔迁移率的能力。
• DC field measurement techniques using conventional laboratory electromagnets work well when measuring materials with mobilities as low as approximately 1 cm²/ Vs (Fig. 2). However, the evolving classes of thermoelectric, photovoltaic and organic electronic materials are characterized by much lower mobilities, which are therefore difficult to measure by this method. Using DC field techniques to extract the relatively small Hall voltage from the misalignment and thermoelectric voltages that are produced by such materials is a non-trivial task.

图2。Mobility ranges for the AC and DC Field Hall

经过验证的交流场厅效应测量的优势

15多年来，日本科学家和材料研究人员一直在使用AC Hall效应测量方法。欧洲杯足球竞彩

Since the Hall voltage is proportional to the magnetic field, when an AC field is applied, the Hall voltage signal will be an AC signal as well. The thermoelectric voltages and misalignment, however, are DC voltages and therefore easy to separate from the AC Hall voltage signal. Some of the advantages of this method are:

• 该方法使用锁定放大器，该放大器可以将所需的AC与具有高偏卡的不希望的直流电压分开。
• Researchers can reliably measure mobilities much lower than those measurable by the DC field technique (Fig. 3).

图3。In low mobility and moderate resistivity (< 1 GΩ) materials, the misalignment voltage - mainly a result of asymmetry in sample contacting - is frequently the predominant contributor to error in DC Hall measurement, limiting resolution of mobility measurement. AC field techniques eliminate this form of error, allowing for significantly lower mobility measurements.

申请

AC字段方法已成功用于各种应用程序，其中包括以下内容：

• 用于替代能源应用的光伏和热电材料的测量，包括无定形硅（A：SI），硒化铜（CIGS）和其他太阳欧洲杯足球竞彩能电池材料，通常具有10个迁移率^-3and 10 cm²/（vs）。
• 该方法对于使用透明导电氧化物（TCO）半导体（例如氧化锌（ZnO），氧化锌），氧化锌（IGZO）和其他具有16至300厘米左右的TCO材料的新显示技术也很有用。欧洲杯足球竞彩²/（vs）。尽管DC测量值很好地处理了高端，但通过使用更高的精度AC测量，低端将受益匪浅。
• 研究人员可以通过使用AC Hall欧洲杯足球竞彩测量更好地理解的另一种类别的材料是有机电子材料，该材料正在研究中用于电子设备，并且具有很小的迁移率，范围为10以下^-3to 1 cm²/（vs）。这se materials, including organic light-emitting diodes (OLEDs), organic field-effect transistors (OFETs) and organic thin-film transistors (OTFTs) are lighter, more flexible and more economical to manufacture than inorganic materials and have high potential in enabling advancement of the electronics market.

仪器

这8400系列大厅效果测量系统utilizes the AC Hall effect to study the electronic and magneto-transport properties of electronic materials. This fully automated and integrated measurement system was developed by Lake Shore Cryotronics in partnership with Toyo Corporation of Japan, a company with several years of experience in AC field technology. The 8400 Series HMS features optional AC field measurement capability that enables measurement of Hall mobilities down to 10^-3cm²/（vs）。它还能够测量在从低至15 K到高至1273 K的温度范围内测量从200GΩ到低至10μΩ的电阻。

With the capability to measure low mobilities, the AC Hall effect method offers solutions to researchers working with novel materials that will be used for next-generation devices and technologies.

This information has been sourced, reviewed and adapted from materials provided by Lake Shore Cryotronics.

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