Silicon diode I–V nuance: According to the more complete (complex) model of a silicon diode, how does the effective barrier/forward potential behave as forward current increases?

Introduction / Context:
The simplistic “0.7 V” rule for silicon diodes is useful, but real diodes follow an exponential I–V relationship. Understanding that forward voltage rises with current (and falls with temperature) is crucial for accurate power dissipation estimates and thermal design in rectifiers and clamps.

Given Data / Assumptions:

• Silicon PN junction diode.
• Room-temperature operation unless otherwise noted.
• Complex model includes series resistance and exponential conduction.

Concept / Approach:
The Shockley diode equation shows current increases exponentially with junction voltage. Practically, as forward current rises, both the junction voltage and series ohmic drop increase, leading to a higher observed forward voltage. Therefore, the “barrier” (effective forward drop) increases somewhat with current, rather than remaining fixed.

Step-by-Step Solution:
Low current region: forward voltage around 0.6–0.7 V.Higher current: additional drop appears due to series resistance and the diode’s exponential law.Net effect: measured forward voltage increases with forward current.Thermal note: rising temperature shifts the curve, reducing forward voltage for a given current.

Verification / Alternative check:
Datasheets include forward I–V curves at multiple temperatures, clearly showing V_F rising with I_F at a given temperature.

Why Other Options Are Wrong:
0 V: a short circuit, not a diode.Fixed 0.7 V: a rough approximation only.Decreases with current: contradicts I–V behavior at constant temperature.

Common Pitfalls:
Using a constant 0.7 V in power calculations at high currents underestimates heat dissipation. Always consult I–V curves for accurate design.

Final Answer:
the barrier potential increases slightly with an increase in current