CYCLOTRON FIR EMISSION FROM HOT-ELECTRONS IN GAAS/GAALAS HETEROSTRUCTURES

We study far infrared emission from GaAs-GaAlAs heterostructures, induced by electric pulses in the presence of a magnetic field and a hydrostatic pressure. Clyclotron masses are measured as functions of 2D electron density in the strong electron heating regime at pressures P = 0 and P = 7 kbar and the detection energy of 4.43 meV. The results are described by an effective two-level k . p theory, which takes consistently into account the effect of band's nonparabolicity in GaAs on electric and magnetic quantization. It is shown that the observed emission spectrum is due to eight transitions between Landau levels (populated up to the optic phonon energy), since under the strong heating conditions the 2D electron gas is nondegenerate. This is independently confirmed by magnetotransport measurements. Very good theoretical description of emission experiments at pressures P = 0 and P = 7 is achieved with the use of bulk GaAs parameters. Theoretical estimations of the heating conditions in crossed magnetic and electric fields indicate that the electric field in our GaAs-GaAlAs structures is highly inhomogeneous.