Answer: Tunnel diodes (Esaki diodes) at forward bias.
- A Standard ohmic resistors, where resistance never decreases with current
- B Tunnel diodes (Esaki diodes) at forward bias
- C Ideal p-n junction diodes under normal forward or reverse bias
- D Ordinary Schottky diodes used for fast rectification
Correct answer: B. Tunnel diodes (Esaki diodes) at forward bias
Explanation: Tunnel diode: at certain forward bias, tunneling current decreases as bias increases (NDR region). Used in oscillators and fast switches.
Conductors have overlapping bands, semiconductors have a small energy gap that can be bridged by heat or doping, and insulators have a large gap that blocks conduction.
Concept context
Band theory, p-n junction, diodes, transistors, logic gates, and integrated circuits.