GATE EC 2015 Set 1 — Question 19

MCQ+1 / -0.33EasyP-N Junction & DiodesElectronic Devices

Electronic Devices → P-N Junction & Diodes

Last updated 5 September 2026

Question

A region of negative differential resistance is observed in the current voltage characteristics of a silicon PN junction if

Correct answer (A) both the P-region and the N-region are heavily doped Solution A tunnel diode exhibits negative differential resistance. This phenomenon occurs when both the p-type and n-type regions of a PN junction are very heavily doped (degenerate doping). This heavy doping results in a very narrow depletion region, which allows for quantum mechanical tunneling of electrons across the junction at low forward bias voltages, creating the characteristic negative resistance region. Turn this into a strength. Explore AI-powered practice and doubt support with Success Tracker.

Review answer and solution without JavaScript

Interactive answer checking needs JavaScript. The published solution is available below.

Correct answer (A) both the P-region and the N-region are heavily doped Solution A tunnel diode exhibits negative differential resistance. This phenomenon occurs when both the p-type and n-type regions of a PN junction are very heavily doped (degenerate doping). This heavy doping results in a very narrow depletion region, which allows for quantum mechanical tunneling of electrons across the junction at low forward bias voltages, creating the characteristic negative resistance region.

Continue learning with Success Tracker

Use Success Tracker to ask about the reasoning, then try another GATE EC question to check your understanding.

AI-powered practice· Unlimited practice on eligible plans

PYQs with solutions: Attempt available previous-year questions, then compare your reasoning with the worked solution. Coverage varies by stream.
Practice that adapts: Choose a topic, work on weaker areas and bookmark questions to revisit. Your attempts feed your progress tracking.
AI doubt support: Ask follow-up questions about a step or concept while practising, instead of stopping at the final answer.

Unlimited practice is available on eligible plans. Free practice and AI usage have limits; check the current plan allowances before choosing.

This page stays readable without an account. AI responses can be wrong; check them against the solution and source material.