Question

1.24P)a) Plot the structure of p-channel MOS-FET (Show semiconductor structure, gate, drain, source and voltage polarities) and summarize the working principle. b) Explain what happens if you change drain source voltage polarity. c) Plot the band diagram, approximate distributions of charge, electric field, and electrostatic potential in the ideal MOS capacitor in inversion for the p-channel case.

Answer 1

Bolution The structure of p-channel The Dram characteristics - MOSFET Iman Sourges) gate (G) Dyon (D) - Vas = -lov SAL 6 IZS102 Vys8 V • Vas - UV pt Diffused channel -2 tige 0 Vos(V) 19 N-type Substrate TS Symbel is :- 1 G Vos consiau VDG = Voo & Vgs =Vgg • When Voe is increased the drain current Is should increase but due the To to the applied Vas , controlled at certain natue. Hence, the gate current control drain current is os the output given in 1. D 1) 01 Va4 carriers leading cuvant To to A The basic structure of p-channel enhance the dram - sounce veltage polarity mert type MOSFET À in MOSFET is kept in such a A lightly doped a-substrate may that the majority change is taken into which canners flow from source to two heavily doped pt Drain. so, if we change the regions are diffused! Drain to sowice voltige pelarity, it will resist the flow of charge decrease in of the magnitude of Draint - sowice voltage These two pt region acts as service further increased thin I, 0, and duain when the gate terminal and the MOSFET will ginen -ve potential Vgg and the go drain source voltage Voo Off mode. [Remember then due to pt region, the holes avoent is changing in this case & only vos increased through the diffused p- pecarity is changed channel the mosfet works in enhancement mode. when the gate erminal is given the potential Vug than the drain source voltage Voo then due to the repulsion, the depletion occurs due to which the flow of current reduces. Thus, mokks in Depletion Vas is not and a Mode

U19 R44 OF MOSCAPACITOR IN PCHANNEL CASE. Flathand 9X; 9x 90 ml 94/ LE Ei Vio Ec Er Ef . Ev voo '90! Ei Ev Inversion, Metal-Oxide p-substrate. Foo VEO, all band remains feat and the semiconductor and its majority ies are in and thermal minality carie Equilibrium, Eq= Intrinsic Energy Energy Ef= Fenni lend Ev - Valance nel band to conduction Band,

bending in and Increasing the negative voltage continues the once ei cross Ef, the minority carrier Choles) exleeds the majority calier at the interface