砷化镓肖特基场效应管有源层中的电子迁移率分布对器件有重要的影响,改变负栅偏压可以测出不同深度处的迁移率,但是由于表面总是处在耗尽状态,因此很难测出表面电子迁移率,本文介绍一种微分直流等效模型,使肖特基势垒可以正偏且较好地包括了栅电流修正.应用这一模型,可以较精确地测出非常接近表面的漂移迁移率和几何磁阻迁移率,模型推导较严密,物理意义清晰. The GaAs Schottky FET in the active layer electron mobility distribution has a significant impact on the device, change the negative gate bias can be measured at different depths of mobility, but the surface is always in a depleted state , So it is difficult to measure the surface electron mobility. This paper presents a differential DC equivalent model that enables the Schottky barrier to be forward biased and includes a good correction of the gate current. Using this model, The drift mobility and the geometrical magnetoresistive mobility very close to the surface, the model derived more stringent, the physical meaning is clear.