The current i flows in response to an applied electric field, with its. The other variation of this type of experiment was. The hall effect theory for a charge moving in a magnetic field, it experiences a force acting at right angles to both its direction and the direction of the magnetic field h. When a current carrying conductor is placed in a magnetic field mutually perpendicular to the direction of current a potential difference is developed at right angle to both the magnetic and electric field. It directly determines both the sign and density of charge carriers in a given sample. The hall effect is the production of a voltage difference the hall voltage across an electrical conductor, transverse to an electric current in the conductor and to an applied magnetic field perpendicular to the current. Mar 24, 2019 for the love of physics walter lewin may 16, 2011 duration. In general, the hall voltage is not a linear function of magnetic field applied, i.
A current can be thought of as a negative charge moving in one direction or as a positive charge moving in the opposite direction. Hall effect applications of hall effect electrical4u. To calculate the hall coefficient and the carrier concentration of the sample material. If an electric currents is made to flow through a conductor in a magnetic field, the magnetic field will exert a transverse force on the moving charge carriers which tends to push them to one side of the conductor. You will then determine the concentration of the free carrier. A buildup of charge at the sides of the conductors will balance this magnetic influence, producing a measurable voltage. In metal it is entirely due to the flow of electrons, in. Mainly lorentz force is responsible for hall effect. Oct 12, 2014 in this experiment you will use the hall effect to measure the strength of magnetic fields.
The hall effect is a galvanomagnetic effect, which was observed for the first time by e. This effect consists in the appearance of an electric field called hall field eh. Pdf the hall effect experiment using new data acquisition. The ends of the hall effect tube a vacuum with a trace of neon gas are connected to a battery. Measure the hall voltage and conductivity for germanium as a function of temperature. Hall observed that when an electrical current passes through a sample placed in a magnetic field, a potential proportional to the current and to the magnetic field is developed across the material in a direction. Physics laboratory manual for engineering undergraduates. Magnetic field is produced by electromagnet operated by 016v, 5a power supply. It directly determines both the sign and density of.
Measurements of the hall voltage are used to determine the density and sign of. Giri department of physics indian institute of technology guwahati a project completed under the curriculum development cell, quality improvement program q. Hall effect september 7, 2015 january 8, 2011 by mini physics imagine a conductor with rectangular crosssection d x t that is parallel to the yz plane with conventional current passing in the positive x direction. The discovery of the ha effect department of physics. Hall observed that when a currentcarrying conductor is placed in a transverse magnetic eld, the lorentz force on the moving charges produces a potential di erence perpendicular to both the magnetic eld and the electric current. The hall effect experiment using new data acquisition and processing methods 33 figure 6. Hall effect experiment department of physics and astronomy. Consider a rectangular conductor of thickness t kept in xy plane. Hall effect is used in an instrument called hall effect multiplier which gives the output proportional to the product of two input signals. This effect consists in the appearance of an electric field called hall field eh r, due to the deviation of the charge carrier trajectories by an external magnetic field. Aug, 2018 hall effect applications of hall effect august, 2018 february 24, 2012 by electrical4u whenever we place a current carrying conductor in a magnetic field, there is a deflection of the charge carriers due influence of magnetic field in the conductor body. Hence in a semiconductor, instead of travelling in a straight line, the electrons and holes will initially take paths as shown by the dotted lines in the figure below. Hall effect, development of a transverse electric field in a solid material when it carries an electric current and is placed in a magnetic field that is perpendicular to the current. What is hall effect and what is the use of hall effect.
Jan 02, 2016 to study hall effect in extrinsic semiconducting samples and determine the type and density of majority charge carriers. Hall observed that when an electrical current passes through a sample placed in a. The electric field, or hall field, is a result of the force that the magnetic field exerts on the moving positive or negative. Finally, in october, 1879, hall measured the lateral potential difference successfully. Notice that the neon in the tube is fluorescing emitting light due to the excitation of the electrical current supplied from the battery. For each curve list the temperature, magnetic field, and the slope of the curve of v hall versus i probe. Note that d is the dimension of the probe, which was measured parallel to the applied magnetic field during the experiment prepare a table that includes the following information, which refers to the six curves plotted in part 2b. Hall effect sensors are based on a thin film of semiconducting material typically indium arsenide in which a voltage perpendicular to an applied current and an applied magnetic field appears fig. This is most evident in a thin flat conductor as illustrated.
She hall effect in semiconductor experimentation lab university. The hall effect was discovered in 1879 by edwin hall 242 when he was studying the force acting on the charged particles under an external electric field e ext and a magnetic field h ext. Hall effect hall effect in conductor, ntype semiconductor. Students will measure hall coefficient and carrier charge concentration in a given semiconductor crystal which will help them to understand important concepts in semiconductor physics. Investigating the hall effect in silver university of virginia.
These steps are completely independent of the type of sample and quantitized to values he2m, where m is an integer. Courtesy the ferdinand hamburger jr archives of the johns hopkins university attracting pole pieces of the electromagnet. When a magnetic field is applied to a current carrying conductor in a direction perpendicular to that of the flow of current, a potential difference or transverse electric field is created across a conductor. The temperature range of this experiment is 77k to 400k at its most extreme. To study hall effect in extrinsic semiconducting samples and determine the type and density of majority charge carriers. The planar hall effect is inherently connected to an anisotropic magnetoresistance amr essentially different longitudinal resistivities for magnetic field aligned or perpendicular to the.
These kinds of sensors with typical dimensions of the sensitive element of 0. Hall effect and resistivity measurements in doped gaas 1 experiment 14 hall effect and resistivity measurements in doped gaas note. It is numerically equal to hall electric field induced in. T32 these results are displeasing results prior results when experiment was conducted manually note. For clarity, the original effect is sometimes called the ordinary hall effect to distinguish it from other hall effects which have. The magnetic force is f m ev d b where v d is the drift velocity of the charge. The hall effect was discovered in 1879 by edwin herbert hall while working on his doctoral degree at the johns hopkins university in baltimore, maryland, usa discovered 18. The transverse voltage hall effect measured in a hall probe has its origin in the magnetic force on a moving charge carrier. Hall observed that when a currentcarrying conductor is placed in a transverse magnetic eld, the lorentz force on the moving charges produces a potential di erence perpendic ular to both the magnetic eld and the electric current. The hall effect in metals and semiconductors in this experiment, students learn about the classical hall effect which is the basis of most sensors used in magnetic field measurements. This is used to select the part of the experiment to perform. To determine the hall voltage developed across the sample material. This experiment introduces students to the hall effect which is a fundamental principle of magnetic field sensing. This experiment demonstrates the effect of lorentz force.
Hall effect hall coefficient higher physics experiments. Pdf the hall effect, in all its variants classic, quantum or fractional quantum, is one of the effects that revolutionized certain areas of physics. Instrument manuals this lab will be graded 30% on theory, 20% on technique, and 50% on analysis. The crystal is covered by a protective layer of paint. This effect is particularly pronounced in thin metals, and is easily observable in a lowdensity plasma an electrically conductive ionized gas, such as a fluorescent light, as in this tutorial.
The hall probe that we will use in this lab is made of a semiconductor. Please read the radiation safety regulations at the back of this book objectives of the experiment the behaviour of the hall voltage in a sample of doped germanium is studied in three different setups as follows. The hall effect, in all its variants classic, quantum or fractional quantum, is one of the effects that revolutionized certain areas of physics, not only theoretically but also in technological. This voltage is a direct measure of the magnetic field as long as the current is constant. All of we know that when we place a current carrying conductor inside a magnetic field, the conductor experiences a mechanical force to a direction depending upon the direction of magnetic field and the direction of current in the conductor.
We will study the hall effect in a parallelepipedic semiconductor sample of sizes a, b, c see figure 1. B magnetic field strength t v drift velocity of electrons ms1 d width of the conductor m obviously, the hall effect gives a larger voltage if the conductor is wide d large and if v is. Which of the following are true statements about the hall effect. Gaas hall element has high sensitivity, wide linear range, and small temperature coefficient. Two solenoids, constant current supply, four probe, digital gauss meter, hall effect apparatus which consist of constant current generator ccg, digital milli voltmeter and hall probe. This is used to select the part of the experiment to perform 1 magnetic field vs current.
For clarity, the original effect is sometimes called the ordinary hall effect to. For the love of physics walter lewin may 16, 2011 duration. It depends on the strength of the magnetic field so it can be used to measure magnetic field strength. In this experiment you will measure the resistivity and the hall coe cient as functions of the temperature, for an aldoped germanium crystal. Physics leaflets solidstate physics conduction phenomena investigating the hall effect in silver objects of the experiment g validation of the proportionality of the hall voltage and the magnetic flux density. Thin film samples consisting of a semiconductor inas and two different metals aluminum and gold are investigated to determine the sign and density of the. Sep 07, 2015 hall effect september 7, 2015 january 8, 2011 by mini physics imagine a conductor with rectangular crosssection d x t that is parallel to the yz plane with conventional current passing in the positive x direction. At this time, hall used thin gold foil to accomplish the experiment. Hall effect experiment utk department of physics and. An effect when occurring when a current carrying conductor is placed in a magnetic field and orientated so that the field is at right angles to the direction of the current. This manual is intended to provide a general guidance for the lab.
Introduction semiconductors exhibit several interesting effects that will be investigated in this lab. Hall effect and its applications in semiconductorsphysics. This apparatus is purposed to help students understand the principle of hall effect, measure the sensitivity of a hall element, and learn how to use a hall element to measure magnetic field intensity. Hall devised an experiment that can be used to identify the sign of the predominant charge carriers in a conducting material. A current i is arranged to flow through the strip from left to right, and the voltage difference between the top and bottom is measured. This slider activate only if hall effect setup is selected.
The potential difference v is a consequence of free electrons in the material being deflected by the magnetic field. The hall effect experiment conducted by edwin hall in 1879 determines the sign of the charge carriers in current flow. The magnetic field is directly out of the page, represented by circled dots. The hall effect 1 background in this experiment, the hall effect will be used to study some of the physics of charge transport in metal and semiconductor samples. Assuming the voltmeter probes are vertically aligned, the voltage difference is zero when b 0. In the present setup, the crystal mount on pcb is placed perpendicular to the pole pieces.
And this is used to select the material for finding hall coefficient and carrier concentration. California polytechnic state university solid state physics laboratory. The potential difference v is a consequence of free electrons in. This is the socalled ordinary hall effect in which the electrons are deflected into the direction of e ext. In this experiment, the hall effect will be used to study some of the physics of charge transport in metal and semiconductor samples. The hall effect refers to the potential difference that builds up across opposing faces of a cuboidal shaped material when it is carrying current and placed in a uniform magnetic field. In this experiment you will use the hall effect to measure the strength of magnetic fields. The quantum hall effect or integer quantum hall effect is a quantummechanical version of the hall effect, observed in twodimensional electron systems subjected to low temperatures and strong magnetic fields, in which the hall conductance. Pdf the hall effect experiment using new data acquisition and. This is known as the hall effect, named after american physicist edwin hall, who discovered the phenomenon in 1879.
Students will measure hall coefficient and carrier charge concentration in a given semiconductor crystal which will help them to understand important concepts in. Physics laboratory manual for engineering undergraduates dr. Ccg constant current generator, j x current density e electron, b applied magnetic field t thickness, w width v h hall voltage. In solid state physics, hall effect is an important tool to characterize the materials especially semiconductors. Reif, fundamentals of statistical and thermal physics introduction in this experiment the resistivity and hall effect in a crystal of ntype. Hall effect ndoped semiconductor se7260 products pasco. If the magnetic field is applied along negative zaxis, the lorentz force moves the charge carriers say electrons toward the ydirection. The hall effect department of physics and astronomy. The fundamental quantum of hall resistance is he2 25,8.
Harsh shukla hall sensor hall effect and its applications hall effect thruster 2. The whole system is mounted in a pen type case for further protection. If an electric current flows through a conductor in a magnetic field, the magnetic field exerts a transverse force on the moving charge carriers which tends to push them to one side of the conductor. From a historical perspective, this experiment was the first to 11. This laboratory manual is based on a manual for a very similiar experiment from the physics 111 advanced undergraduate laboratory at uc berkeley see references. The theoretical background for this experiment is discussed at length in refs.
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