Calculating Electron-Hole Pairs

Material

Density
ρ
(g/cm³)

Ionization
energy
E
(eV)

Generation rate
g = 6.25 X 10¹⁵ρ/E
(no. electron-hole pairs/gray-cm³)

P-n junction induced current for 1000 gray/s
I_P
μA/cm³

Silicon	2.328	3.6	4.0 X 10¹⁵	6.41
Gallium arsenide	5.32	4.8	7.0 X 10¹⁵	11.2
Germanium	5.33	2.8	1.2 X 10¹⁶	19.2
Silicon dioxide	2.27	18	8.2 X 10¹⁵	—
air	1.205 X 10^–3	34	2.2 X 10¹¹	—

This table shows how to obtain the number of electron-hole pairs generated per unit volume per unit radiation dose for three different semiconductors (as well as for oxide and air for comparison). In the last column, this generation rate has been converted to the induced current per unit of semiconductor volume (in cubic microns) for a fixed dose rate of 1000 gray per second. For other dose rates, the induced current scales linearly.

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