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# How to derive Hall's coefficient for a semiconductor?

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View Full Interview# Which semiconductor have positive temperature coefficient?

With the increase in temperature if the resistance increases or the current in the circuit decreases then it is said to be have positive temperature coefficient . But in semi…-conductors with the increase in temperature the electrons present in the valance band are excited and they would enter the conduction band for conduction . As the no. of charge carriers always increase in a semi-conductor , implies that the current always increases with the increase in temperature so the semi-conductor can never have positive temperature coefficient

# Why do the semiconductors have negative temperature coefficient whereas the metals have positive values?

Semiconductors: When temperature increases, more electrons jump to conduction band from valance bond. Hence resistance decreases. Metals: Already plenty of electrons are there… in conduction band. When temperature increases, the electrons in conduction band of metal vibrate and collide each other during their journey. Hence the the resistance of metal increases with increase of temperature. S.Lakshminarayana

# Why semiconductor has negative temperature coefficient of resistance?

Because if temperature of semiconductors is increased then number of free electrons per unit volume increases its conductivity increases and resistivity decreases.

# What is a semiconductor?

A semiconductor is a solid whose electrical conductivity is in between that of a conductor and that of an insulator, and can be controlled over a wide range, either perm…anently or dynamically. Semiconductor materials can be elements (e.g. germanium, silicon), compounds (e.g. copper oxide, lead sulfide), or metal alloys (e.g. gallium arsenide, gallium aluminum indium phosphide). A pure semiconductor material is a very poor conductor or even an insulator, but when impurities called dopants are added it can become a quite good conductor. There are two classes of dopants: N type and P type. N type dopants create negatively charged current carriers (i.e. free electrons) in the semiconductor, just like ordinary conductors use. P type dopants create positively charged current carriers (i.e. holes) in the semiconductor. (Note: dopants do no make the semiconductor material electrically charged.) Because semiconductors have two different types of current carrier (not just the one that ordinary conductors have), it is possible to create junctions between differently doped parts of semiconductor material that conduct in one direction but not the other, or due to quantum mechanical effects do other useful things. Semiconductor is a material that has the electrical conductivity between that of a conductor and an insulator. Silicon, germanium and graphite are some examples of semiconductors. Source : Physics and Radio-Electronics ( website)

# What is negative temperature coefficient of semiconductor?

The resistance of the semiconductor material decreases with increase in temperature,this phenomenon is said to be negative temperature coefficient of semiconductor.

# What is the effect of temperature on hall coefficient of a lightly doped semiconductor?

Hall coefficient of the given sample falls with rise in temperature

# What are semiconductors?

Semiconductors are insulators at low temperatures and reasonably good conductors at higher temperatures. semiconductors whose ability to conduct electric lies between those o…f conductor and insulator Additional: Common semiconductors include silicon and germanium, which are tetra-valent, that is each atom has four electrons in its outer orbit. In the normal crystalline form, the atoms form covalent bonds where adjacent atoms share an electron. Electrons thus bound are not free to move and are not affected by an electric field. These bonds are fairly weak, and are easily broken. At any temperature above absolute zero, many of the bonds are broken leaving electrons free to move. So, as temperature increases, the semiconductor material becomes a better and better conductor. This is an intrinsic, or pure semiconductor. So, the above statement " Semiconductors are insulators at low temperatures and reasonably good conductors at higher temperatures." is absolutely true. As used in electronics, impurities are intentionally introduced (doped) into the semiconductor. When penta-valent (5 outer electrons) elements such as Arsenic and Antimony are used, the semiconductor has many free electrons, and is said to be n-type. If tri-valent (3-outer electrons) elements such as Boron, Gallium and Indium are used, the material is electron starved, and is said to be p-type. If we dope one side of a semiconductor block such that it is n-type, and the other side p-type, a so-called semiconductor junction is formed. This is the building block for all modern electronics such as the diode, transistor and integrated circuit (IC).

# Is semiconductor is positive temperature coefficient?

No. Semiconductor has negative temp coefficient, because increase in temp causes the increase in the k.e of the electrons bu t not in the no of electrons . these highly energi…sed electronsel increase current, & in terms conductivity.

# What information about a chemical reaction is derived from the coefficients in a balanced equation?

Coefficients are used to represent multiple molecules of formula units.

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In Algebra

# How do you get the coefficients?

measure them

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In Algebra

# What a coefficient?

a number or quantity placed (generally) before and multiplying another quantity, as 3 in the expression 3x.

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# Why semiconductors have negative temperature coefficient?

Because as they get colder their resistance increases and vise versa.

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In Physics

# How do you derive coefficient of viscosity?

consider two layers of fluid from a fixed layer. Then according to Newtons Law of viscosity, the viscous force(F) acting tangentially is directly proportional to the area of t…he layer(A) and is also directly proportional to dv/dx. F directly proportional to A..................(1) F directly proportional to dv/dx...................(2) therefore from (1) and (2) F directly proportional to Adv/dx removing proportionality sign, we get F=coefficient of viscosity multiplied by Adv/dx hence, coefficient of viscosity =Fdx/Adv

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In Algebra

# What is a coefficient?

A coefficient is a number in front of a variable (i.e. multiplied by it). For example, in the expression x2 - 10x + 25, the coefficient of x2 is 1 and the coefficient of x is… -10. The third term, 25, is a constant. If the expression were -x2 + 10x + 25, the coefficient of x2 would be -1, and the coefficient of x would be 10.