Sequential Single-Phonon Emission in GaAs-AlxGa1−xAsTunnel Junctions

Abstract

Periodic structure is observed in the tunneling current from heavily doped (${n}^{+}$) GaAs through ${\mathrm{Al}}_{x}{\mathrm{Ga}}_{1\ensuremath{-}x}\mathrm{As}$ into lightly doped (${n}^{\ensuremath{-}}$) GaAs at 1.6 K in magnetic fields large enough for magnetic freezeout of electrons to occur in the ${n}^{\ensuremath{-}}$-GaAs. Sixteen periods are observed for $\ensuremath{-}0.6\mathrm{V}<{V}_{G}<0\mathrm{V}$. 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.