The transport properties of electrons in a heterostructure high electron mobility transistor are analyzed by considering the capture and escape phenomena as scattering events in Monte Carlo simulation. Through the variation of the equivalent charge in time, the drain current of an AlInAs/InGaAs/InP quantum-well device with planar doping is deduced for given drain and gate voltages. We studied the energy distribution of carriers in the device and we compared the results to those obtained by other quantum mechanical treatment and the classical treatment of the confinement. We demonstrated that by using our capture procedure for the quantum mechanical treatment, carriers have higher energy values than in the case of classical treatment and therefore the current values are different by an amount of 30&percent;–40&percent;. ©1997 American Institute of Physics.