Holzer sensor is a kind of magnetic field sensor based on the Holzer effect. Hall effect is a magnetoelectric effect a, this phenomenon is hall (A.H.Hall 1855 - 1938) in 1879 in the conductive mechanism of metal research found. Later this effect was observed in the semiconductor and conductive fluid, and semiconductor Hall effect than metal much stronger, the use of this phenomenon from the hall element and widely application in the field of industrial automation technology, detection technology, information processing. Holzer effect is a basic method to study the properties of semiconductor materials. The Holzer coefficient, which is determined by the Holzer effect experiment, can determine the conductive type, carrier concentration and carrier mobility of the semiconductor materials.

The principle of Holzer effect is known, the size of Holzer electric potential depends on: Rh for the Holzer constant, it is related to the semiconductor material; I for the Holzer component bias current; B for the magnetic field strength; D for the thickness of the semiconductor material.

For a given Holzer device, when the bias current I is fixed, the UH will depend entirely on the measured magnetic field strength B.

Hall effect

A Holzer component generally has four lead terminals, two of which are Holzer components of the bias current I input, and the other two are the output of Holzer voltage. If the two output constitutes the outer loop, it will produce Holzer current. Generally speaking, the bias current is usually given by the external reference voltage source. If the precision demand is high, the reference voltage source is replaced by the constant current source. In order to achieve high sensitivity and some of the hall element sensor surface with high permeability permalloy; this kind of sensor Hall potential larger, but at about 0.05T saturated, only for in low volume limit, small range use.

At both ends of the semiconductor wafer through to control current I, and in the direction perpendicular to the sheet applied magnetic induction B uniform magnetic field, in the perpendicular to the direction of the current and the magnetic field, the potential difference is uh Hall voltage.

There is a Holzer semiconductor chip in the magnetic field, a constant current I from A to B through the film. In under the action of the Lorentz force, I of the electron flow through the semiconductor Hall to the side of the offset to the film in the CD direction have a potential difference, this is called the Hall voltage.

Hall voltage changes with changes in the magnetic field strength, magnetic field is stronger, higher voltage, the magnetic field is weaker, lower voltage and Hall voltage value is very small, usually only a few millivolts, but is amplified by the amplifier integrated circuit, can make the voltage amplification to strong signal output. If the Holzer integrated circuit from sensing, need to use a mechanical method to change the magnetic induction intensity. The following figure shows the method is to use a rotating impeller as the control of magnetic flux switch, when the impeller blades in the magnet and Holzer integrated circuit between the air gap, the magnetic field deviation from the integrated chip, Holzer voltage disappear. In this way, the output voltage of the Holzer integrated circuit can be expressed in a certain position of the impeller drive shaft, and the use of the working principle can be used for the action of the Holzer integrated circuit chip. Holzer effect sensor is a passive sensor, it must have an additional power to work, this feature allows it to detect low speed operation.

Hall Effect Sensor

Holzer leaves 1- semiconductor element 2- permanent magnet 3- blocking lines

Hall effect

The Holzer effect is essentially the deflection of the motion of charged particles caused by the Lorentz force in magnetic field. When charged particles (electrons or holes) is constrained in the solid material, the deflection leads to the accumulation of positive and negative charges in the direction of the vertical current and magnetic field, so additional lateral electric field is formed. For shown in figure of the semiconductor sample, if in the X direction through to current is, in the Z direction and magnetic field B, in the Y direction that sample a, a 'electrodes on both sides of the began accumulation heterocharge and produce corresponding to the additional electric field. The direction of the electric field depends on the type of the sample. Obviously, the electric field is to prevent the carrier from continuing to offset to the side, [1]

When the carrier by the transverse electric field force and the Lorentz force is equal to eEH, the sample charge accumulation on both sides can reach equilibrium, it is

Among them, EH is the Holzer electric field, and V is the average drift velocity of the carrier in the current direction. The width of the sample is B, the thickness is D, and the carrier concentration is n.

By the two type available

Holzer VH (voltage the voltage between A and A 'electrode) and ISB product is proportional to the thickness of the sample is inversely proportional to d. Said the proportion coefficient is the hall coefficient, it is an important parameter to reflect the strength of the material, Hall effect, as long as the measured VH (V) and know IIS (ANN), B (Gaussian) and D (CM) can be calculated by the formula of Rh (cm / Coulomb