Sequential single-phonon emission in GaAs-AlxGa1-xAs tunnel junctions

Periodic structure is observed in the tunneling current from heavily doped (n+) GaAs through AlxGa1-xAs into lightly doped (n-) GaAs at 1.6 K in magnetic fields large enough for magnetic freezeout of electrons to occur in the n - GaAs. Sixteen periods are observed for -0.6 V< VG<0 V. The phase and the voltage periodicity, 0.036 V, are independent of magnetic field. The mechanism appears to involve LO-phonon emission events by ballistic electrons. This is the first observation of sequential single-phonon emission observed in electron transport. © 1984 The American Physical Society.