Download presentation
Presentation is loading. Please wait.
2
MOS capacitor before joining The metallic gate may be replaced with a heavily doped p+ polysilicon gate. The Fermi energy levels are approximately at the same level.
3
Positive electron energy
4
MOS capacitor after joining Assume that there is no charge in the oxide layer
5
MOS capacitor energy levels
7
MOS capacitor p type semiconductor voltage bias effects E G V
8
MOS capacitor p type semiconductor voltage bias effects –battery switched G V E
9
MOS capacitor n type semiconductor voltage bias effects G V E
10
MOS capacitor n type semiconductor voltage bias effects –battery switched E G V
11
MOS capacitor after joining Assume that there is charge in the oxide layer
12
G V MOS capacitor p type semiconductor gate voltage V G = V Flatband
13
MOS capacitor p type semiconductor gate voltage V G = V T “threshold” G V
14
MOS capacitor –charge distribution..
16
Problem 6.1 Charge distributions are depicted in an MOS capacitor. 1) Is the semiconductor n or p type? 2) Does the bias make it an accumulation mode, depletion mode or an inversion mode?
17
Problem 6.1 Charge distributions are depicted in an MOS capacitor. 1) Is the semiconductor n or p type? 2) Does the bias make it an accumulation mode, depletion mode or an inversion mode?
18
Electric field due to charges
19
. MOS capacitor – changing charge distribution with changing voltage accumulation mode.
20
. MOS capacitor – changing charge distribution with changing voltage depletion mode.
21
MOS capacitor – changing charge distribution with changing voltage
23
definition Approximate proportion of charge located at x
24
Problem 6.22 Using superposition, find the dependence of the “flat bad voltage” as the charge density changes. Nonuniform charge density @ x Change of flat band voltage Superimposition applies
25
Problem 6.23 Using superposition, find the dependence of the “flat bad voltage” for a particular charge density profiles.. Charges located just at the interface
26
Charge density is nonuniform
27
Problem 6.28 Consider the high-frequency capacitance- voltage relationship. Locate the inversion; threshold; depletion; flat band, and accumulation points.
Similar presentations
![EE415 VLSI Design The Devices: MOS Transistor [Adapted from Rabaey’s Digital Integrated Circuits, ©2002, J. Rabaey et al.]](/16/5062541/big_thumb.jpg "EE415 VLSI Design The Devices: MOS Transistor [Adapted from Rabaey’s Digital Integrated Circuits, ©2002, J. Rabaey et al.]>")
