  We analyze the operation of the hot-electron FET bolometers with the graphene
channels (GCs) and the gate barrier layers (BLs). Such bolometers use the
thermionic emission of the hot electrons heated by incident modulated THz
radiation. The hot electron transfer from the GC into the metal gate. As the
THz detectors, these bolometers can operate at room temperature. We show that
the response and ultimate modulation frequency of the GC-FET bolometers are
determined by the efficiency of the hot-electron energy transfer to the lattice
and the GC side contacts due to the 2DEG lateral thermal conductance. The
dependences of these mechanisms on the band structure and geometrical
parameters open the way for the GC-FET bolometers optimization, in particular,
for the enhancement of the maximum modulation frequency.
