Semiconductor Device Principles Flashcards

What is the primary effect of increasing temperature on the reverse saturation current (I₀) of a silicon diode?

Answer: I₀ approximately doubles for every 10°C rise

Reverse saturation current approximately doubles for every 10°C increase in temperature due to increased minority carrier generation.

In a PNP bipolar junction transistor operating in active mode, the emitter current is 10 mA and the base current is 0.2 mA. What is the collector current?

Answer: 9.8 mA

By KCL, IC = IE – IB = 10 mA – 0.2 mA = 9.8 mA.

Which semiconductor parameter defines the average time a minority carrier exists before recombining?

Answer: Minority carrier lifetime

Minority carrier lifetime (τ) is the average time a minority carrier survives before recombining with a majority carrier.

A Zener diode is used primarily in which region of its V-I characteristic?

Answer: At the Zener breakdown voltage

Zener diodes are designed to operate at the reverse breakdown (Zener) voltage, maintaining a stable reference voltage.

What is the typical value of the Early voltage (VA) for a small-signal BJT, and what does a larger VA indicate?

Answer: Typically 50–200 V; larger VA means higher output resistance and less channel-length modulation

Early voltage is typically 50–200 V for BJTs; a higher VA means the output characteristics are more horizontal, indicating higher output resistance.

In an N-channel JFET, what happens to the drain current when the gate-to-source voltage (VGS) is made more negative?

Answer: Drain current decreases toward zero

Making VGS more negative widens the depletion region in the N-channel JFET, constricting the channel and reducing drain current toward IDSS cutoff.

Which effect describes the increase in BJT collector current due to base-width narrowing as VCE increases?

Answer: Early effect

The Early effect (base-width modulation) causes collector current to increase slightly as VCE increases, narrowing the neutral base width.