How useful is Hooge´s empirical relation

Merits of Hooge´s empirical relation for 1/f noise are investigated: S_R/R²= α/Nf with N the number of free charge carriers and α a parameter with a range: 10^-8 <; α <; 10^-2, depending on temperature, lattice quality and mobility μ. Parameters affecting the α-value are discussed. We propose a model explaining: α ~ μ^-m with m ≈ 3 as observed in undoped quantum wells (QW) and m ≈ 1 attributed to screening as observed in 2DEG´s of gated QW. Hooge´s relation implies that 1/f noise is a bulk effect. The normalized noise in films for bias, frequency and unit area as C_us [cm²] is proportional to the sheet resistance R_sh[Ω]. The proportionality factor K [cm²/Ω] = C_us/R_sh is also a figure of merit, applicable for materials even if N is unknown. The K- and α-values are a useful metrics.