lecture15annotat

lecture15annotat - 6.012 - Microelectronic Devices and...

Info iconThis preview shows pages 1–7. Sign up to view the full content.

View Full Document Right Arrow Icon
6.012 - Microelectronic Devices and Circuits - Fall 2005 Lecture 15-1 Lecture 15 - The pn Junction Diode (I) I-V Characteristics November 1, 2005 Contents : 1. pn junction under bias 2. I-V characteristics Reading assignment: Howe and Sodini, Ch. 6, §§ 6.1-6.3
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
6.012 - Microelectronic Devices and Circuits - Fall 2005 Lecture 15-2 Key questions Why does the pn junction diode exhibit current rec- tification? Why does the junction current in forward bias increase qV as exp kT ? What are the leading dependences of the saturation current (the factor in front of the exponential)?
Background image of page 2
6.012 - Microelectronic Devices and Circuits - Fall 2005 Lecture 15-3 1. PN junction under bias Focus on intrinsic region: p n metal contact to n side metal contact to p side ( N a ) ( N d ) x = 0 n type p type p type x x (a) (b) Upon application of voltage: electrostatics upset: depletion region widens or shrinks current flows (with rectifying behavior) carrier charge storage
Background image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
6.012 - Microelectronic Devices and Circuits - Fall 2005 Lecture 15-4 Carrier profiles in thermal equilibrium: log p o , n o p o n o N d n i 2 N d x 0 N a n i 2 N a J h diff J h drift J e diff J e drift Inside SCR in thermal equilibrium: dynamic balance be- tween drift and diffusion for electrons and holes. | J drif t | = | J dif f |
Background image of page 4
ction ess 6.012 - Microelectronic Devices and Circuits - Fall 2005 Lecture 15-5 Carrier concentrations in pn junction under bias: for V> 0, φ B V ↓⇒ | E SCR |↓⇒| J drif t |↓ log p, n p o p n o n N d n i 2 N d x 0 N a n i 2 N a J h diff J h J h drift J e diff J e drift J e Current balance in SCR broken: | J drif t | < | J dif f | Net diffusion current in SCR into QNR’s minority carrier inje exc xcess minority carrier concentrations in QNR’s minority carrier injection Lots of majority carriers in QNR’s current can be high.
Background image of page 5

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
action 6.012 - Microelectronic Devices and Circuits - Fall 2005 Lecture 15-6 for V< 0, φ B V ↑⇒ | E SCR |↑⇒| J drif t |↑ N a N d n i 2 n i 2 N d N a n x log p, n p o p n o 0 J h J h diff J h drift J e diff J e J e drift Current balance in SCR broken: | J drif t | > | J dif f | Net drift current in SCR minority carrier extr deficit minority carrier extraction from QNR’s of minority carrier concentrations in QNR’s Few minority
Background image of page 6
Image of page 7
This is the end of the preview. Sign up to access the rest of the document.

Page1 / 20

lecture15annotat - 6.012 - Microelectronic Devices and...

This preview shows document pages 1 - 7. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online