The number of silicon atoms per m 3 is 5 × 10 28 . This is doped simultaneously with 5 × 10 22 atoms per m 3 of Arsenic and 5 × 10 20 per m 3 atoms of Indium. Calculate the number of electrons and holes. Given that ni = 1.5 × 10 16 m –3 . Is the material n-type or p-type?

Question

Philoid · Accepted Answer

Given,

Number of Silicon atoms per m³ = 5 × 10²⁸

Number of Arsenic atoms per m³ (n_As) = 5 × 10²²

Number of Indium atoms per m³ (n_In) = 5 × 10²⁰

Intrinsic charge carrier concentration (n_i) = 1.5 × 10¹⁶ m^-3

So, number of electrons per m^-3 (n_e) = n_As – n_i

i.e., n_e = 5 × 10²² – 1.5 × 10¹⁶ = 4.99 × 10²² m^-3

If n_h is the number of holes per m^-3, then according to Mass-action law,

n_i² = n_en_h

So, n_h = n_i²/n_e

i.e., n_h =

So, n_h= 4.5 × 10⁹ m^-3

The number of electrons is higher than the number of holes. So, the given material is n-type.

NOTE: Arsenic is pentavalent and Indium is trivalent. In an n-type semiconductor, electrons are the majority charge carriers i.e., n_e≫n_h. In a p-type semiconductor, holes are the majority charge carriers i.e., n_h ≫ n_e.

The number of silicon atoms per m3 is 5 × 1028. This is doped simultaneously with 5 × 1022 atoms per m3 of Arsenic and 5 × 1020 per m3 atoms of Indium. Calculate the number of electrons and holes. Given that ni = 1.5 × 1016 m–3. Is the material n-type or p-type?

The number of silicon atoms per m³ is 5 × 10²⁸. This is doped simultaneously with 5 × 10²² atoms per m³ of Arsenic and 5 × 10²⁰ per m³ atoms of Indium. Calculate the number of electrons and holes. Given that ni = 1.5 × 10¹⁶ m^–3. Is the material n-type or p-type?