1 / 8

Reminder: Quiz #4 on April 4; Office Hours Update and MOS Capacitor Lecture Overview

This announcement serves as a reminder that Quiz #4 is scheduled for Wednesday, April 4. Please note that there will be no office hours or Coffee Hour on that day. Tsu-Jae will hold office hours tomorrow, April 3, from 11 AM to 12 PM. The lecture will cover the MOS Capacitor's structure, energy band diagram, and related readings from Chapter 16.1-16.2 of the textbook. Key topics include heavily doped poly-Si gate materials, band bending, and energy band diagrams.

patia
Télécharger la présentation

Reminder: Quiz #4 on April 4; Office Hours Update and MOS Capacitor Lecture Overview

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. ANNOUNCEMENTS Reminder: Quiz #4 on Wednesday 4/4 No Office Hour or Coffee Hour on Wednesday Tsu-Jae will hold office hour tomorrow (4/3) 11-12 OUTLINE The MOS Capacitor: Structure Energy band diagram Reading: Chapter 16.1-16.2 Lecture #29 EE130 Lecture 29, Slide 1

  2. MOS Capacitor Structure • Typical MOS capacitors and transistors in ICs today employ • heavily doped polycrystalline Si (“poly-Si”) film as the gate-electrode material • n+-type, for “n-channel” transistors (NMOS) • p+-type, for “p-channel” transistors (PMOS) • SiO2 as the gate dielectric • band gap = 9 eV • er,SiO2 = 3.9 • Si as the semiconductor material • p-type, for “n-channel” transistors (NMOS) • n-type, for “p-channel” transistors (PMOS) MOS capacitor (cross-sectional view) GATE xo + VG _ Si EE130 Lecture 29, Slide 2

  3. MOS Equilibrium Energy-Band Diagram semiconductor metal oxide n+ poly-Si SiO2 EC p-type Si EC=EFM EFS EV EV EE130 Lecture 29, Slide 3

  4. Guidelines for Drawing MOS Band Diagrams • Fermi level EF is flat (constant with distance x) in the Si • Since no current flows in the x direction, we can assume that equilibrium conditions prevail • Band bending is linear in the oxide • No charge in the oxide => dE/dx = 0 so E is constant => dEc/dx is constant • From Gauss’ Law, we know that the electric field strength in the Si at the surface, ESi, is related to the electric field strength in the oxide, Eox: E E E EE130 Lecture 29, Slide 4

  5. MOS Band-Diagram Guidelines (cont.) • The barrier height for conduction-band electron flow from the Si into SiO2 is 3.1 eV • This is equal to the electron-affinity difference (cSi and cSiO2) • The barrier height for valence-band hole flow from the Si into SiO2 is 4.8 eV • The vertical distance between the Fermi level in the metal, EFM, and the Fermi level in the Si, EFS, is equal to the applied gate voltage: EE130 Lecture 29, Slide 5

  6. Special Case: Equal Work Functions FM = FS EE130 Lecture 29, Slide 6

  7. General Case: Different Work Functions E0 E0 E0 E0 EE130 Lecture 29, Slide 7

  8. Flat-Band Condition EE130 Lecture 29, Slide 8

More Related