The intrinsic carrier concentration in silicon at T = 300 K is known to be n i = 1 . 5 × 10 16 m - 3 . A sample of silicon is doped with 5 × 10 22 m - 3 arsenic (a group V element). Under these circumstances the concentrations of electrons ( n ) and holes ( p ) in the sample are

n = 5 × 10 22 m - 3 , p = 4 . 5 × 10 9 m - 3

n = 1 . 5 × 10 22 m - 3 , p = 0 . 5 × 10 9 m - 3

n = 1 . 5 × 10 16 m - 3 , p = 1 . 5 × 10 16 m - 3

n = 4 . 5 × 10 9 m - 3 , p = 5 × 10 22 m - 3

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Holes are majority carriers in n-type semiconductor while electrons are majority carries in p-type semiconductor.

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Important Questions on Semiconductor Electronics: Materials, Devices and Simple Circuits

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Physics>Electronics>Semiconductor Electronics: Materials, Devices and Simple Circuits>Extrinsic Semiconductor

A donor impurity results in

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Physics>Electronics>Semiconductor Electronics: Materials, Devices and Simple Circuits>Extrinsic Semiconductor

Mobility of electrons in a semiconductor is defined as the ratio of their drift velocity to the applied electric field. If, for an

N

-type semiconductor, the density of electrons is

10^{19} m^{- 3}

and their mobility is

1.6 m^{2} V^{- 1} s^{- 1}

, then the resistivity of the semiconductor (since it is an

N

-type semiconductor contribution of holes is ignored) is close to:

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Physics>Electronics>Semiconductor Electronics: Materials, Devices and Simple Circuits>Extrinsic Semiconductor

An intrinsic semiconductor is converted into

n

-type extrinsic semiconductor by doping it with:-

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Physics>Electronics>Semiconductor Electronics: Materials, Devices and Simple Circuits>Extrinsic Semiconductor

An extrinsic semiconductor with electrons as majority carriers can be obtained by doping Ge or Si with

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Physics>Electronics>Semiconductor Electronics: Materials, Devices and Simple Circuits>Extrinsic Semiconductor

n -

type semiconductor contains:

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Physics>Electronics>Semiconductor Electronics: Materials, Devices and Simple Circuits>Extrinsic Semiconductor

In a semiconductor, the concentration of minority carriers depends mainly on

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Physics>Electronics>Semiconductor Electronics: Materials, Devices and Simple Circuits>Extrinsic Semiconductor

For a

p -

type semiconductor, which of the following statements is true?

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Physics>Electronics>Semiconductor Electronics: Materials, Devices and Simple Circuits>Extrinsic Semiconductor

In a p-type semiconductor, the concentration of holes is

2 \times 10^{15} {cm}^{- 3} .

The intrinsic carrier concentration is

2 \times 10^{10} {cm}^{- 3} .

The concentration of electrons will be

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Physics>Electronics>Semiconductor Electronics: Materials, Devices and Simple Circuits>Extrinsic Semiconductor

What are the majority and minority carriers in a p-type semiconductors

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Physics>Electronics>Semiconductor Electronics: Materials, Devices and Simple Circuits>Extrinsic Semiconductor

Intrinsic carrier concentration of a silicon sample at

300 K

1.5 \times 10^{16} m^{- 3} .

After doping, the number of majority carriers is

2.25 \times 10^{20} m^{- 3} .

The minority carrier density is

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Physics>Electronics>Semiconductor Electronics: Materials, Devices and Simple Circuits>Extrinsic Semiconductor

The electron concentration in an undefined

n

-type semiconductor is the same as hole concentration in a undefined

p

-type semiconductor. An external field (electric) is applied across each of them. Compare the currents in them.

MEDIUM

Physics>Electronics>Semiconductor Electronics: Materials, Devices and Simple Circuits>Extrinsic Semiconductor

A semiconductor has equal electron and hole concentration

6 \times 10^{8} m^{- 3}

. On doping with a certain impurity electron concentration increases to

9 \times 10^{12} m^{- 3}

. Calculate the new hole concentration. Also identify the new semiconductor.

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Physics>Electronics>Semiconductor Electronics: Materials, Devices and Simple Circuits>Extrinsic Semiconductor

Statement I: By doping silicon semiconductors with pentavalent material, the electrons density increases.

Statement II: The $n -$ type of semiconductor has a net negative charge.

In the above statements, choose the most appropriate answer from the options given below:

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Physics>Electronics>Semiconductor Electronics: Materials, Devices and Simple Circuits>Extrinsic Semiconductor

For extrinsic semiconductors; when doping level is increased;

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Physics>Electronics>Semiconductor Electronics: Materials, Devices and Simple Circuits>Extrinsic Semiconductor

Which of the following statement is false?

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Physics>Electronics>Semiconductor Electronics: Materials, Devices and Simple Circuits>Extrinsic Semiconductor

n -

type silicon, which of the following statements is true?

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Physics>Electronics>Semiconductor Electronics: Materials, Devices and Simple Circuits>Extrinsic Semiconductor

The dominant contribution to current comes from holes in case of

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Physics>Electronics>Semiconductor Electronics: Materials, Devices and Simple Circuits>Extrinsic Semiconductor

The intrinsic carrier concentration in silicon at

T = 300 K

is known to be

n_{i} = 1.5 \times 10^{16} m^{- 3}

. A sample of silicon is doped with

5 \times 10^{22} m^{- 3}

arsenic (a group

V

element). Under these circumstances the concentrations of electrons

(n)

and holes

(p)

in the sample are

MEDIUM

Physics>Electronics>Semiconductor Electronics: Materials, Devices and Simple Circuits>Extrinsic Semiconductor

When indium is doped to silicon as impurity, the resulting material is

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Physics>Electronics>Semiconductor Electronics: Materials, Devices and Simple Circuits>Extrinsic Semiconductor

The density of an electron-hole pair in pure germanium is

3 \times 10^{16} m^{- 3}

at room temperature. On doping with aluminium, the hole density increases to

4.5 \times 10^{22} m^{- 3}

. Now the electron density (in

m^{- 3}

) in doped germanium will be

Holes are majority carriers in n-type semiconductor while electrons are majority carries in p-type semiconductor.

Important Questions on Semiconductor Electronics: Materials, Devices and Simple Circuits

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