Magnetophonon resonance effects in the phonon emission by a hot two-dimensional electron gas in a GaAs-AlGaAs heterojunction

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Abstract
The dominant energy relaxation process for hot electrons (Te>50 K) in GaAs-AlGaAs heterojunctions is generally believed to be through the emission of optical phonons. In magnetic fields satisfying the condition nh omega c=h omega LO the energy relaxation rate is expected to be enhanced by magnetophonon resonance. The authors have heated the two-dimensional electron gas (2DEG) in a single GaAs-AlGaAs heterojunction by applying pulsed electric fields in the region of 104 V m-1 across the conducting channel. The optical phonons emitted rapidly decay into acoustic modes which they observe using CdS bolometers. Peaks in the amplitude of the detected phonon pulse as a function of magnetic field are observed which the authors attribute to magnetophonon resonant emission. The positions of the peaks are consistent with the LO phonon frequency in bulk GaAs.