X-rays in Silicon

Check signal in silicon from X-rays for 1 keV and 10 keV

From fig. 26.13 p. 18, ch 26 "Passage of particles through matter" it is shown that in this energy range photons interact via the photo electric effect, namely all the photon energy goes into an electron. The energetic electron then travels a short distance compared to the detector thickness and gives up it's energy to ionization.

Fig. 26.15, p. 20, ch 26 "Passage of particles through matter" gives absorption length from which we can get the probability of the photon giving up it's energy vs passing on through with no interaction.

absorption length for 1 and 10 keV photons

the fraction of photons absorbed in distance x, measured in g/cm^2

Thickness of the active layer, this will include the epi layer plus part of the substrate. Some electrons can diffuse out of the substrate.

Average energy to create an electron hole pair

Absorption probability for 10 mm of silicon with 1 and 10 keV photons

Current from X-rays on the silicon

n rate of electrons hiting the silicon surface

E is the photon energy

qe is the charge on the electron