Interaction of Phonons with the 2-DEG in a MODFET
Using nanosecond pulse techniques, we have studied the direct emission and absorption of phonons by the same two-dimensional electron gas (2DEG) in a GaAs/AlGaAs modulation-doped field effect transistor structure (MODFET) . Pulsed emission of phonons from a heterojunction has been observed by Chin et al , and by Hawker et al , and absorption by Eisenstein et al . In a MODFET, the additional feature of a Schottky gate allows the carrier concentration and hence the Fermi energy to be varied. It also enables the 2DEG contact resistance to be determined independently during a run at helium temperatures, essential for quantitative analysis.
KeywordsPulse Emission Phonon Drag Longitudinal Phonon Phonon Absorption Boxcar Integrator
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