R H = p μ μ h 2 − − n μ μ e 2 e ( p μ μ h + n μ μ e ) 2 or equivalently R H = p − − n b 2 e ( p + n b ) 2 with b = μ μ e μ μ h . Here n is the electron concentration, p the hole concentration, μ e the electron mobility, μ h the hole mobility and e the elementary charge.