Hall Effect in a Semiconductor

这个项目正在构建一个实验来测量半导体晶体中的霍尔效应。该实验取代了目前测量等离子体中霍尔效应的实验，由于缺乏对等离子体流体动力学的理解，学生无法准确地评估他们的数据，因此受到了严重的限制。在一个半导体实验中的霍尔效应中，学生测量了锗晶体的电阻率和霍尔电压，当磁场横向施加到通过晶体的电流上时，霍尔电压就产生了。在液氮和室温之间的不同温度下进行这些测量，学生们确定了锗的带隙值，晶体中杂质的密度，电阻率和电子和空穴迁移率的温度依赖性，以及磁电阻对温度和外加磁场的依赖性。通过霍尔效应实验，学生不仅扩展了半导体物理的基础知识，而且更好地了解了现代凝聚态物质研究中使用的技术。他们学习如何测量和控制液氮和高于室温之间的温度，以及如何在材料中进行电气测量，包括零测量。这个实验也提高了他们的数据简化和分析技能。

This project is constructing an experiment to measure the Hall effect in a semiconductor crystal. This experiment replaces the current experiment to measure the Hall effect in a plasma, which is seriously limited by the inability of students to evaluate their data accurately in the absence of an understanding of plasma hydrodynamics. In the Hall effect in a semiconductor experiment students make measurements of the resistivity of a germanium crystal and the Hall voltage that develops when a magnetic field is applied transverse to the applied current through the crystal. Taking these measurements at a variety of temperatures between liquid nitrogen and room temperatures, the students determine the value of the band gap in germanium, the density of impurities in the crystal, the temperature dependence of the resistivity and the electron and hole mobilities, and the dependence of the magnetoresistance on temperature and applied magnetic field. Through the Hall effect experiment, students not only extend their knowledge of the fundamentals of semiconductor physics but also become better acquainted with the techniques used in modern condensed matter research. They learn how to measure and control temperatures between liquid nitrogen and higher than room temperatures and how to make electrical measurements, including null measurements, in materials. The experiment also improves their data reduction and analysis skills.