An improved method for determining the inversion layer mobility of electrons in trench MOSFETs

For the first time trench sidewall effective electron mobility (μ_eff) values were determined by using the split capacitance-voltage (CV) method for a large range of 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. In conclusion, the results show that (1) the split CV method is an accurate method for determining μ_eff(E_eff) data in trench MOSFETs, (2) the {100} μ_eff data approach published data of planar MOSFETs for high E_eff and (3) the mobility behavior can be explained with generally accepted scattering models for the entire range of E_eff. The results are important for the optimization of trench power devices.