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Examoogle • User • info@examoogle.com • EE-2024-8821
Chapter 1 of 12 • Page 1 of 248🔒 Protected PDF • Watermarked
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If the temperature of a diode increases, then leakage current ____.
Remains the same
Decreases
Increases
Becomes zero
Increases
Quick Summary: The leakage current (also known as reverse saturation current, $I_0$) in a semiconductor diode increases significantly with a rise in temperature. This occurs because thermal energy facilitates the generation of more minority charge carriers, which are the primary contributors to leakage current.
The leakage current (also known as reverse saturation current, I0) in a semiconductor diode increases significantly with a rise in temperature. This occurs because thermal energy facilitates the generation of more minority charge carriers, which are the primary contributors to leakage current.
I0∝Tne−kTEg — Dependence of reverse saturation current on temperature
Inew≈Iold⋅2°10ΔT — Rule of thumb: leakage current doubles for every 10°C rise in Ge diodes
In a p-n junction diode, the reverse saturation current I0 is dependent on the concentration of minority carriers (electrons in p-type, holes in n-type). As temperature increases, the covalent bonds break due to thermal agitation, generating electron-hole pairs throughout the crystal. Since these minority carriers can easily cross the depletion barrier under reverse bias, their increased density leads to a higher reverse leakage current.
Reverse saturation current is primarily due to thermally generated minority carriers.
For Silicon diodes, the leakage current approximately doubles for every 6°C to 10°C rise in temperature.
Germanium diodes exhibit much higher leakage currents than Silicon diodes at the same temperature.
Excessive leakage current can lead to thermal runaway in high-power applications.
Provides a predictable way to monitor thermal stability
Allows usage of diodes as temperature sensors in specific biased modes
Degrades the rectification efficiency at high temperatures
Increases power dissipation and risk of thermal runaway
Temperature compensation circuits
Thermal monitoring sensors
High-temperature power electronics design
The exponential dependence on temperature is a fundamental characteristic of semiconductor devices.
Option A is incorrect because leakage current is highly temperature-dependent.
Option B is incorrect because leakage current increases, not decreases, with thermal energy.
Option D is incorrect as leakage current is non-zero even at room temperature.
C is correct — The leakage current in a diode increases with temperature due to the increased rate of thermally generated minority charge carriers.
Always remember that while forward resistance decreases with temperature, reverse leakage current increases exponentially, which is the primary reason why Silicon is preferred over Germanium in high-temperature environments.