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Semiconductor Device Principles Flashcards

7 cards from real ISCET practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.

Read the first 7 Semiconductor Device Principles flashcards as text

  1. What is the purpose of the intrinsic layer in a PIN diode?

    Answer: To provide a wide depletion region that reduces junction capacitance and enables fast switching at RF frequencies

    The intrinsic (I) layer widens the depletion region, lowering capacitance and allowing PIN diodes to function as RF switches or attenuators.

  2. In a common-emitter BJT amplifier, which parameter is primarily responsible for the upper cutoff frequency limitation at high frequencies?

    Answer: Miller-multiplied collector-base capacitance (Cµ)

    The Miller effect multiplies the collector-base capacitance Cµ by (1 + |Av|), creating a dominant pole that limits high-frequency response.

  3. What does the threshold voltage (VTH) of a MOSFET depend on?

    Answer: Gate oxide thickness, substrate doping, flat-band voltage, and oxide charge

    VTH is determined by oxide thickness (tox), substrate doping (NA), flat-band voltage (VFB), and interface/oxide charges.

  4. A Schottky diode differs from a p-n junction diode primarily because:

    Answer: It is a metal-semiconductor junction with majority carrier conduction and no minority carrier storage

    Schottky diodes are metal-semiconductor junctions relying on majority carriers, eliminating minority carrier storage and enabling very fast switching.

  5. The small-signal output resistance (ro) of a BJT in the common-emitter configuration is approximately:

    Answer: VA / IC

    The output resistance ro ≈ VA / IC, where VA is the Early voltage and IC is the quiescent collector current.

  6. What is the significance of the depletion approximation used in p-n junction analysis?

    Answer: It assumes the depletion region has zero free carriers and the neutral regions have no charge

    The depletion approximation assumes the depletion region is fully depleted of free carriers (abrupt edges) and neutral regions are charge-free, simplifying junction width calculations.

  7. In a depletion-mode MOSFET, the device conducts when VGS is:

    Answer: Zero or negative (for N-channel), with a pre-existing channel at VGS = 0

    Depletion-mode MOSFETs have a built-in channel that conducts at VGS = 0 and can be pinched off by applying a negative VGS (for N-channel).