THE ELECTRON-MOBILITY TRANSITION IN N-GAAS HEAVILY-DOPED CHANNELS

Low-field electron transport properties in heavily doped n-GaAs channe ls at 300 K are investigated by Monte Carlo simulation. The matrix ele ment for electron-impurity scattering is obtained from the Fourier-tra nsformed Coulomb potential accounting for the screening effects of the two-dimensional electron gas. The effects of the screening and the im purity profile are analysed. Electron mobility is calculated for sever al values of sheet electron density and n-GaAs thickness. For low shee t electron density, the calculated mobility increases with the sheet e lectron density and is almost independent of n-GaAs thickness. For hig h sheet electron density, the mobility approaches a constant value and becomes independent of sheet electron density. These findings are exp lained for the first time as a transition from a two- to three-dimensi onal nature and are well confirmed by our experiments.