Sharp transmission coefficient in GaAs/AlAs resonant tunneling diodes with (411)A superflat interfaces grown by molecular beam epitaxy

In order to understand the improved I-V characteristics of GaAs/AlAs resonant tunneling diodes (RTDs) with (411)A superflat interfaces, transmission coefficient (T*T) was deduced from the second derivative (d(2)I/dV(2)) of the observed IV curves. The peak width (full-width at half maximum, FWHM) of the transmission coefficient was found to be 8.6 meV, which was 18% smaller than that (10.5 meV) of the RTD simultaneously grown on a conventional (100) GaAs substrate. Photoluminescence (PL) measurements for the GaAs/AlAs double barrier structures of the RTDs themselves also showed a narrower linewidth for the (411)A sample (FWHM = 7.2 meV) than for the (100) sample (10.6 meV). This result suggests that electrons tunneling through the barriers are as sensitive to the interface roughness as excitons in the quantum well.