A model of degradation of AlGaAs-heterostructures is presented. The model of dissipative processes was extended to the case of a diffusion-blured aluminum profile. The definition of the Г-Х-mixing operator is generalized for potentials without explicit heterojunctions. The effect of degradation processes on inelastic scattering is taken into account by applying the diffusion equation to the optical potential profile. The self-consistency algorithm was optimized in order to reduce the calculation time. This paper proposes a faster method based on the reduction in the number of calculated integrals for electrons density. A number of test structures were simulated via developed algorithm. The deviation of the calculation results from the experimental data on the curvature of CVC initial section does not exceed 3%. Thus, we can conclude that it is expedient to use the model to calculate the kinetics of heterostructures СVC initial section at elevated temperatures, including within the framework of the task of predicting the GIC and MIC UHF reliability indicators based on multilayer AlGaAs-heterostructures.