Question

A semiconductor X is made by doping a germanium crystal with arsenic(Z.= 33).
A second semiconductor Y is made by doping germanium with indium(Z = 49).The two are joined end to end and connected to a battery as shown in the adjacent figure. Which of the following statement is correct?

• A. X is p-type, Y is n-type and the junction is forward biased
• B. X is n-type,Y is p-type and the junction is forward biased.
• C. X is p-type, Y is n-type and the junction is reverse biased.
• D. X is n-type, Y is p-type and the junction is reverse biased.

Answer 1

The correct option is D X is n-type, Y is p-type and the junction is reverse biased.

We know,

On doping a semiconductor by 13 group element it becomes p-type

and by 15 group elements it becomes n-type.

Here,

X is n-type, and Y is p-type,

And as the positive terminal of battery is connected to p-type and

negative is connected to n-type,

The diode is reverse biased,

Hence option $\text{D}$ is the correct answer.