EE5508_Semiconductor_Fundamentals-C2_1

EE5508_Semiconductor_Fundamentals-C2_1 - EE5508-PII-C2-1 1...

Info iconThis preview shows pages 1–10. Sign up to view the full content.

View Full Document Right Arrow Icon

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

View Full DocumentRight Arrow Icon

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

View Full DocumentRight Arrow Icon

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

View Full DocumentRight Arrow Icon

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

View Full DocumentRight Arrow Icon

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

View Full DocumentRight Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: EE5508-PII-C2-1 1 EE5508 Semiconductor Fundamentals Part II Chapter 2-1 2011 Spring (G.C. Liang) Source P ++ Channel I/N OX OX Drain N ++ gate gate Schedule EE5508-PII-C2-1 2 2011 Spring (G.C. Liang) 2011/3/1 Lecture 7 Chapter 1 2011/3/8 Lecture 8 2011/3/15 Lecture 9 2011/3/29 Lecture 10 Chapter 2 2011/4/5 Lecture 11 2011/4/12 Lecture 12 Chpater 3 EE5508-PII-C2-1 2011 Spring (G.C. Liang) 3 Outline • Fundamentals – Optical processes – Light emission • Devices – LEDs – Lasers – Photodiodes • Photodetectors • Photovoltaics EE5508-PII-C2-1 2011 Spring (G.C. Liang) 4 Light? What is light?  Electromagne2c wave (Classical point of view)  photon (Quantum Theory) Maxwell Equations ∇  D= ρ ;  D= ε  E ;  D: electrical flux density ∇  B =0;  B= μ  H ;  B: magnetical flux density ∇ ×  E=- ∂  B ∂ t ∇ ×  H = ∂  D ∂ t +  J assume ρ = 0 and  J = ∇ × ∇ ×  E=- ∂ ∂ t ∇ ×  B ∇ × ∇ ×  E=(- ∇ 2 E + ∇ ( ∇ E )) = −∇ 2 E (  ∇  D=0) ∇ ×  B = ∇ × ( μ  H ) = μ ∂  D ∂ t ∇ × ∇ ×  E=- ∂ ∂ t ∇ ×  B → ∇ 2 E = μ ∂ 2  D ∂ t 2 = μ ε ∂ 2  E ∂ t 2 = 1 V 2 ∂ 2  E ∂ t 2 → E = e i 2 πν ( t − x / V ) = e i ( ω t − kx ) ; EE5508-PII-C2-1 2011 Spring (G.C. Liang) 5 Photon energy=  ω Electromagnetic wave (photond) can interacts with electrons in semiconductor  light absorption or emission. EE5508-PII-C2-1 2011 Spring (G.C. Liang) 6 Relationships between Optical Constants Absorption coefficient We describe the radiation as a plane wave of frequency propagating in the x direction with a velocity v : ν ε = ε e i 2 πν [ t − x / V ] where v = c / n c , with c: velocity of propagation in vacuum and n c = n − i κ (the index of refraction) → 1 V = n c c = n c − i κ c Then, ε = ε e i 2 π vt e i 2 π vxn / c e − 2 π v κ x / c The last term is a damping factor. EE5508-PII-C2-1 2011 Spring (G.C. Liang) 7 The fraction of the incident power available after propagating a distance x: power ∝ ε 2 P ( x ) P (0) = ε ( x ) 2 ε (0) 2 = e − α x α = 4 πνκ c ; α : absorption coefficient. κ : the imaginary part of n c , is called the extinction coefficient. We relate the complex dielectric constant with n , κ as follows: ε c = ε 1 + i ε 2 ε c = n c ∴ε = n 2 −κ 2 ε 2 = − 2 n κ EE5508-PII-C2-1 2011 Spring (G.C. Liang) 8 Reflection coefficient x y z t=0 In region I, E = ( E in e − ikz + E r e ikz ) H = ( H in e − ikz − H r e ikz ) = ( E in / η 1 e − ikz − E r / η 1 e ikz ) In region II, E = ( E t e − ikz ) H = E t / η 2 e − ikz Z=0 I II at boundary E i + E r = E t E i − E r η 1 = E t η 2 ⇒ E i + E r E i − E r = η 2 η 1 E r E i = η 2 −η 1 η 1 + η 2 ≡ r E t E i = 2 η 2 η 1 + η 2 ≡ τ EE5508-PII-C2-1 9 2011 Spring (G.C. Liang) η 1 = μ 1 ε 1 and η 2 = μ 2 ε 2 assume μ 1 ≈ μ 2 r = n 1 − n 2 n 1 + n 2 ⇒ R = rr...
View Full Document

This note was uploaded on 04/15/2011 for the course EE 5508 taught by Professor Liang during the Spring '11 term at National University of Singapore.

Page1 / 30

EE5508_Semiconductor_Fundamentals-C2_1 - EE5508-PII-C2-1 1...

This preview shows document pages 1 - 10. Sign up to view the full document.

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