Electronics and Communication Engineering - Electronic Devices and Circuits - Discussion
Discussion Forum : Electronic Devices and Circuits - Section 8 (Q.No. 41)
41.
Consider the following statements about conditions that make a metal semiconductor contact rectifying
- N type semiconductor with work function φs more than work function φM of metal
- N type semiconductor with work function φs less than work function φM of metal
- P type semiconductor with work function φs more than work function φM of metal
- P type semiconductor with work function φs less than work function φM of metal.
Discussion:
1 comments Page 1 of 1.
Abhijeet said:
6 months ago
A metal-semiconductor (M-S) contact becomes rectifying (Schottky contact) when a potential barrier (Schottky barrier) forms at the junction, preventing free carrier movement in one direction while allowing it in the other.
The condition for a rectifying contact depends on the relative work function (φ) of the metal (φM) and the semiconductor (φS).
Rectifying Contact (Schottky Contact) Conditions:
For an N-type semiconductor:
If φS > φM → Electrons in the semiconductor face a potential barrier at the junction, making the contact ohmic (not rectifying).
If φS < φM → A barrier forms for electrons, leading to a rectifying contact.
For a P-type semiconductor:
If φS > φM → A barrier forms for holes, leading to a rectifying contact.
If φS < φM → Holes move easily, making the contact ohmic (not rectifying).
Evaluating the Given Statements:
N-type with φS > φM →(Ohmic contact, not rectifying)
N-type with φS < φM → (Schottky/rectifying contact)
P-type with φS > φM →(Schottky/rectifying contact)
P-type with φS < φM → (Ohmic contact, not rectifying)
Thus, statements 2 and 3 are correct.
Final Answer: 2 and 3 are correct.
The condition for a rectifying contact depends on the relative work function (φ) of the metal (φM) and the semiconductor (φS).
Rectifying Contact (Schottky Contact) Conditions:
For an N-type semiconductor:
If φS > φM → Electrons in the semiconductor face a potential barrier at the junction, making the contact ohmic (not rectifying).
If φS < φM → A barrier forms for electrons, leading to a rectifying contact.
For a P-type semiconductor:
If φS > φM → A barrier forms for holes, leading to a rectifying contact.
If φS < φM → Holes move easily, making the contact ohmic (not rectifying).
Evaluating the Given Statements:
N-type with φS > φM →(Ohmic contact, not rectifying)
N-type with φS < φM → (Schottky/rectifying contact)
P-type with φS > φM →(Schottky/rectifying contact)
P-type with φS < φM → (Ohmic contact, not rectifying)
Thus, statements 2 and 3 are correct.
Final Answer: 2 and 3 are correct.
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