The Solid State

Question 89

What are extrinsic semi-conductor?

An extrinsic semiconductor is an improved intrinsic semiconductor with a small amount of impurities added by a process, known as doping, which alters the electrical properties of the semiconductor and improves its conductivity. Introducing impurities into the semiconductor materials (doping process) can control their conductivity.
Question 90

What is Photovoltaic.

Photovoltaics (PV) is a method of generating electrical power by converting solar radiation into direct current electricity using semiconductors that exhibit the photovoltaic effect. Example-amorphous silica.
Question 91

Although pure silicon is an insulator, then how does it behave as a semiconductor on heating.

On heating some covalent bonds among silicon atoms break on heating and electrons become free to move under applied field, hence silicon behaves like semi-conductor at high temperature.
Question 92

What is meant by tetrahedral void in a close-packed structure?

 It is the empty space between three spheres in one layer and one sphere in the layer above it or one sphere in the layer below it is called a tetrahedral void

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