The results of theoretical and experimental studies of impact ionization processes and charge carrier heating in multi-valley AIIIBV semiconductors at high electric field are presented and their relationship with the features of the band structure is discussed. A role of subsidiary L- and X-valleys, complex structure of the valence band and orientation dependence of the ionization coefficients are taken into account. A new approach to the choice of semiconductor materials with a large ratio of the ionization coefficients of holes and electrons to create the noiseless avalanche photodiodes due to monopolarity of hot charge carrier multiplication is proposed. Keywords: impact ionization, multi-valley semiconductors, band structure, monopolarity of multiplication, avalanche photodiodes.