Baumann, E.E.BaumannGiorgetta, F.R.F.R.GiorgettaHofstetter, D.D.HofstetterWu, H.H.WuSchaff, W.J.W.J.SchaffEastman, L.F.L.F.EastmanKirste, LutzLutzKirste2022-03-032022-03-032005https://publica.fraunhofer.de/handle/publica/20986710.1002/pssc.200460611We report on intersubband absorption and photovoltage measurements on regular GaN/AlN-based superlattice structures at 1.55 µm. For high barriers, the photovoltage peaks at a higher energy than the absorbance spectrum due to the decrease of the tunnelling probability. The observed photovoltage is thus the macroscopic manifestation that the 2-dimensional electron gas at the top of the superlattice gets depleted by a vertical transport of electrons.en667journal article