  We analyze the two-dimensional electron gas (2DEG) heating by the incident
terahertz (THz) radiation in the field-effect transistor (FET) structures with
the graphene channels (GCs) and the black-phosphorus and black-arsenic gate
barrier layers (BLs). Such GC-FETs can operate as bolometric THz detectors
using the thermionic emission of the hot electrons from the GC via the BL into
the gate. Due to the excitation of plasmonic oscillations in the GC by the THz
signals, the GC-FET detector response can be pronouncedly resonant, leading to
elevated values of the detector responsivity. The lateral thermal conductivity
of the 2DEG can markedly affect the GC-FET responsivity, in particular, its
spectral characteristics. This effect should be considered for the optimization
of the GC-FET detectors.
