Improved method for determining inversion layer mobility of electrons in trench MOSFETs

Trench sidewall effective electron mobility (μ_eff) values were determined by using the split capacitance-voltage (CV) method for a large range of the transversal effective field (E_eff) from 0.1 up to 1.4 MV/cm. The influences of crystal orientation, doping concentration and, for the first time, temperature were investigated. Results show that the split CV method is an accurate method for determining μ_eff (E_eff) data in trench MOSFETs; the {100} μ_eff data approaches published data on planar MOSFETs for high E_eff; and mobility behaviour can be explained with generally accepted scattering models for the entire range of E_eff. The results are important for the optimisation of trench power devices.