Discrete electroluminescence lines in sub-micron p-i-n resonant tunnelling diodes

We have fabricated GaAs/AlAs p-i-n double barrier resonant tunnelling diodes with active lateral dimensions down to 0.25μm² using optical lithography and wet etching. Many devices have been investigated and systematic variations in the quantum well emission have been observed as the device size is decreased. We observe a red shift of the quantum well recombination lines. In addition a new line is observed at lower energy in the spectra of the smallest devices. The quantum well luminescence efficiency is found to be constant down to the smallest device size.