Question

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 n_i = 1.5× 10¹⁶m^-3 . Is the material n-type or p-type?

Answer 1

n_e = 5 × 10²² – 5 × 10²⁰ 

= (5 - 0.05) × 10²² 

= 4.95 × 10²²m⁻³

∴ n_h = \(\frac{n^2_i}{n_e}\)

= \(\frac{(1.5\times 10^{16})^2}{4.95\times 10^{-22}}\)

= 4.54 × 10⁹m^-3

As n_e>nh, 

So the material is n- type semiconductor.