This paper presents the results of studies of sandwich and planar bolometric structures based on aSi:H and VO2 films accordingly. From the point of view of the TCR and resistivity value combanation both materials completely satisty the requirements of microbolometric array. Sandwiches constructed to act as an optical cavity absorb 80% of radiation at 8 mikron wavelength. It is shown that the planar structures absorption of 50-80% can be reached in the 8,5-10 mikron band.