Flash Memory…and a tour through FETs

Junction Field Effect Transistor

Metal Oxide Semiconductor Field Effect Transistor

Actual MOSFET Devices

Single MOSFET on Intel chip Enhancement MOSFET

MOSFET Motor Control

Circuit component Motor Control Circuit

Floating Gate MOSFET = Flash

+++++ Assume:VDS =VD - VS =+12V

What happens if?:VGS =VG – VS= +12 V

Then what happens?:to ‘jailed’ electrons ifVGS is set to 0V?

Reading Memory State

Change in Threshold Voltage due to Screening Effect of Floating GateRead mode: Apply intermediate voltage, check whether current is flowing or not

Writing Memory State

Control gate voltage determines whether electrons are injected to, or push/pulled out of floating gate.

Block Structure

Writing block structure: The ole 2-step

Step 1: Set all bits to 1 (clear out electrons from floating gate)Step 2: Set selected bits to 0 (inject electrons from control to floating gate)

1 2

Voila – flash memory stick

Citations/Image Sources• http://www.learnabout-electronics.org/fet_01.php (JFETs)• http://

volga.eng.yale.edu/index.php/Main/Semiconductors#MOSFET• http://www.electronics-tutorials.ws/transistor/tran_7.html

(MOSFET motor control)• http://www.engadget.com/2011/10/31/engadget-primed-ssds

-and-you/

• https://www.youtube.com/watch?v=msi5GDz9JIw (hyperscience youtube channel – reading flash contents)