NCERT Physics Class 12 Exemplar Ch 14 Semiconductor Electronics Materials Devices and Simple Circuits Part 6 (For CBSE, ICSE, IAS, NET, NRA 2022)

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Q 36 Suppose a β€˜n’ -type wafer is created by doping Si crystal having with 1ppm concentration of As. On the surface ppm Boron is added to create region in this wafer. Considering , (i) calculate the densities of the charge carriers in the regions. (ii) Comment which charge carriers would contribute largely for the reverse saturation current when diode is reverse biased.

Ans:

In β€˜n’ region; number of e– is due to As:

The minority carriers (hole) is

Similarly, when Boron is implanted a β€˜p’ type is created with holes

This is far greater than that existed in β€˜n’ type wafer on which Boron was diffused.

Therefore, minority carriers in created β€˜p’ region

(ii) Thus, when reverse biased , holes of β€˜n’ region would contribute more to the reverse saturation current than minority of p type region.

Q 37 An X-OR gate has following truth table:

Title: Table of an X-Or Gate Has Truth Table
ABY
000
011
101
110

It is represented by following logic relation

Build this gate using AND, OR and NOT gates.

Ans:

It is Represented by Following Logic Relation