Undergraduate course on semiconductor device Physics-II

Explore induced and implanted channels in mosfets, contrast enhancement and depletion modes, and explain inversion layers, mos capacitor behavior, and the role of gate and threshold voltages in the channel.

Explore how depletion and enhancement MOSFETs differ in drain current and channel formation, and define threshold voltage as the minimum gate bias to establish or disable conduction.

Explore the three-dimensional mosfet structure on a silicon substrate, contrasted with its two-dimensional representation, and highlight channel length, oxide thickness, and gate material options like metal, aluminium, or polysilicon.

Explain p-mosfet characteristics in enhancement and depletion modes, including negative threshold voltages and the onset of drain current, with three-terminal representations, saturation and linear regions.

Derive the MOSFET current equation in saturation and linear regions, linking drain current to W/L, mobility, oxide capacitance, and gate voltage through inversion layer concepts.

Explore threshold tailoring via shallow boron implantation beneath the oxide to form a negative charge sheet that shifts the MOSFET threshold voltage toward a positive value.

Understand the body bias effect, or substrate bias, and how bulk potential VB modifies the depletion region between source and bulk, shifting the threshold voltage.

This lecture introduces the bipolar junction transistor, its three-terminal two-junction structure with emitter, base, and collector, and explains the emitter-base and base-collector junctions, current directions, and common configurations.

Explore the basic operation of a bipolar junction transistor, including forward bias of the emitter-base junction, minority-carrier injection, and their sweep into the collector under reverse saturation.

Explore the common-base current gain in a BJT, defined by the transport factor alpha. Relate collector current to emitter and base currents via alpha and gamma.

Revisit emitter efficiency gamma by defining it as the ratio of emitter injection current to total emitter current, and show how base and emitter doping affect gamma.

Explore how minority carrier concentrations vary exponentially near a p-n junction under forward and reverse bias, with carrier injection, diffusion in the neutral base, and saturation effects.

this lecture presents the Ebers-Moll model of a bipolar transistor as two back-to-back diodes, linking emitter and collector currents via alpha factors and junction interaction.

Explore how the input characteristics of a common emitter transistor shift with collector voltage due to the Early effect, illustrating input curves, forward bias, and base-emitter behavior.

Explore the avalanche multiplication and breakdown mechanisms in bipolar transistors, including base-open and emitter-open configurations, and derive the current gain m = 1/(1−α) under breakdown conditions.

Analyze how a bipolar transistor's neutral base governs injected minority-carrier electrons and diffusion. Use maximum electron concentration and diffusion coefficient to estimate diffusion current density, noting linear approximation is invalid.