Lecture9-P-N+Junction+2

# Lecture9-P-N+Junction+2 - ECE 3040 Dr Ying Zhang Georgia...

This preview shows pages 1–13. Sign up to view the full content.

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

View Full Document

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

View Full Document

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

View Full Document

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

View Full Document

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

View Full Document

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

View Full Document
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: ECE 3040 - Dr. Ying Zhang Georgia Tech ECE 3040: Microelectronic Circuits Lecture 9 Reading: Pierret 5.6, 6.1 ECE 3040 - Dr. Ying Zhang Georgia Tech Recapture pn Junction Under Equilibrium ECE 3040 - Dr. Ying Zhang Georgia Tech Recapture Built-In Potential ⎥ ⎥ ⎦ ⎤ ⎢ ⎢ ⎣ ⎡ − = ) ( ) ( ln p n bi x n x n q kT V ⎥ ⎦ ⎤ ⎢ ⎣ ⎡ = 2 ln i D A bi n N N q kT V non-degenerate case n(x n )=N D n(-x p )=n i 2 /N A ECE 3040 - Dr. Ying Zhang Georgia Tech Recapture ( ) ( ) ⎪ ⎪ ⎪ ⎩ ⎪ ⎪ ⎪ ⎨ ⎧ ≥ − ≤ ≤ ≤ − − ≤ ≤ − + − = ⎪ ⎩ ⎪ ⎨ ⎧ ≥ − ≤ ≤ ≤ ≤ ≤ − − = n p n n o S D p p o S A n p n D p A x x and x x for x x for x x K qN x x for x x K qN E x x and x x for x x for qN x x for qN ε ε ρ Quantitative electrostatic relationship with the depletion approximation: Since E (x=0- )= E (x=0 + ) N A x p =N D x n ECE 3040 - Dr. Ying Zhang Georgia Tech Recapture Quantitative electrostatic relationship with the depletion approximation: ( ) ( ) ⎪ ⎪ ⎪ ⎩ ⎪ ⎪ ⎪ ⎨ ⎧ ≥ − ≤ ≤ ≤ − − ≤ ≤ − + = n p n n o S D bi p p o S A x x and x x for x x for x x K qN V x x for x x K qN x V 2 2 ) ( 2 2 ε ε ( ) ( ) ( ) bi D A D A o S n p bi D A A D o S p bi D A D A o S n V N N N N q K x x W V N N N N q K x and V N N N N q K x + = + = + = + = ε ε ε 2 2 2 ECE 3040 - Dr. Ying Zhang Georgia Tech ¡ pn Junction with Applied Voltage ¡ pn Junction I-V Characterstics Agenda ECE 3040 - Dr. Ying Zhang Georgia Tech Depletion Region Approximation: Step Junction Solution V bi V bi |V A | V bi |V A | V bi V A =0 : No Bias V A <0 : Reverse Bias V A >0 : Forward Bias ECE 3040 - Dr. Ying Zhang Georgia Tech Depletion Region Approximation: Step Junction Solution ( ) ( ) ( ) ( ) ( ) ( ) A bi D A D A o S n p A bi D A A D o S p A bi D A D A o S n V V N N N N q K x x W V V N N N N q K x and V V N N N N q K x − + = + = − + = − + = ε ε ε 2 2 2 Thus, only the boundary conditions change resulting in direct replacement of V bi with (V bi -V A ) ECE 3040 - Dr. Ying Zhang Georgia Tech Step Junction Solution: What does it mean? Consider a p + -n junction (heavily doped p-side, normal or lightly doped n side). ECE 3040 - Dr. Ying Zhang Georgia Tech Step Junction Solution: What does it mean? E fp -E fn =-qV A Fermi-level only applies to equilibrium (no current flowing) Majority carrier Quasi-fermi levels ECE 3040 - Dr. Ying Zhang Georgia Tech P-n Junction I-V Characteristics Electron Diffusion Current Electron Drift Current Hole Diffusion Current Hole Drift Current In Equilibrium, the Total current balances due to the sum of the individual components ECE 3040 - Dr. Ying ZhangECE 3040 - Dr....
View Full Document

## This note was uploaded on 09/05/2009 for the course ECE 3040 taught by Professor Hamblen during the Spring '07 term at Georgia Tech.

### Page1 / 28

Lecture9-P-N+Junction+2 - ECE 3040 Dr Ying Zhang Georgia...

This preview shows document pages 1 - 13. Sign up to view the full document.

View Full Document
Ask a homework question - tutors are online