lit theory of led diode
(a) p-n junction under zero bias
(b) p-n junction under forward bias
The relationship between wave length and electricity voltage
Eg=hv/q=hc/(λq)
λ=hc/(qEg)=1240/Eg(nm)
Eg:gap
h= Planck constant=4.13*10-15eV·s
c= light speed = 2.998*108m/s
λ= wave length
substrate energy gap
| Material of substrate | Energy gap | Wave length |
| GaP | 2.24eV | 550nm |
| AIAs | 2.09eV | 590nm |
| GaAs | 1.42eV | 870nm |
| InP | 1.33eV | 930nm |
| AIGaAs | 1.42 ~ 1.61eV | 770-870nm |
| AIGaInP | 1.9~2.2eV | 620~580nm |
| GaN | 3.0~3.6eV | 380~550nm |
| SiC | 3.2`~3.8eV | 380~550nm |
| Year | Material | Wave Length | Light Efficiency |
| 1960’S | GaAsP | 650nm | 0.1lm/W |
| 1970’S | InGaAs | 610nm | 1lm/W |
| 590nm | |||
| 565nm | |||
| 1980’S | AIGaAs | 630nm | 10lm/W |
| 1990’S | AIInGaP | 630nm | 100lm/W |
| 610nm | |||
| 590nm | |||
| 1990’S
|
InGaN | 380nm | 50lm/W |
| 460nm | |||
| 520nm |