3D Time-of-flight distance measurement with custom - Universität ...

54 CHAPTER 3
(a)
Figure 3.3 Optical absorption. (a) Semiconductor under illumination.
(b) Exponential decay of photon flux. [Sze].
The absorption coefficient and hence the penetration depth depends on the light’s
wavelength. The longer the wavelength the deeper in the semiconductor
photoconversion takes place. This behavior is shown in Figure 3.4.
penetration depth (um)
20.0
17.5
15.0
12.5
10.0
7.5
5.0
2.5
Jellison empirical model
0.0
300 400 500 600 700 800 900
wavelength (nm)
Figure 3.4 Optical penetration depth of light into silicon. Theory and practical
measurements differ for long wavelengths. The available models
predict a deeper penetration depth than can be observed by
measurements. (Dashed: theoretical model, solid: measured data.)
[JE1], [JE2].
(b)