A detailed Monte Carlo simulation of hot-electron transport at 77K in a AlGaAs/GaAs quantum well has been carried out in the bulk-phonon approximation taking into account quasi-two-dimensional electron-electron scattering along with other quasi-two-dimensional scattering mechanisms and the effects of degeneracy, but neglecting dynamic screening and plasmon interactions. It is shown that for an intermediate range of AlGaAs donor concentrations (10¹⁷-10¹⁸ cm^-3) a scattering-induced negative differential resistance (SI-NDR) occurs as previously predicted. The threshold for the onset of SI-NDR is significantly less than the thresholds for either inter-valley or real-space transfer; hence the latter mechanisms are thereby delayed to higher fields. It is pointed out that SI-NDR has a much faster relaxation time than either inter-valley or real-space transfer.