MONTE-CARLO SIMULATION OF ELECTRON-DRIFT VELOCITY IN LOW-TEMPERATURE-GROWN GALLIUM-ARSENIDE IN A SCHOTTKY-BARRIER MODEL

We present a method of simulating the electron transport in low-temper ature-grown GaAs by the Monte Carlo method. Low-temperature-grown GaAs contains microscopic inclusions of As and these inhomogeneities rende r impossible the standard Monte Carlo mobility simulations. Our method overcomes this difficulty and allows the quantitative prediction of e lectron transport on the basis of principal microscopic material param eters, including the impurity and the precipitate concentrations and t he precipitate size. The adopted approach involves simulations of a si ngle electron trajectory in real space, while the influence of As prec ipitates on the GaAs matrix is treated in the framework of a Schottky- barrier model. The validity of this approach is verified by evaluation of the drift velocity in homogeneous GaAs where excellent agreement w ith other workers' results is reached. The drift velocity as a functio n of electric field in low-temperature-grown GaAs is calculated for a range of As precipitate concentrations. Effect of compensation ratio o n drift velocity characteristics is also investigated. It is found tha t the drift velocity is reduced and the electric field at which the on set of the negative differential mobility occurs increases as the prec ipitate concentration increases. Both these effects are related to the reduced electron mean free path in the presence of precipitates. Addi tionally, comparatively high low-field electron mobilities in this mat erial are theoretically explained.