AlGaAs/GaAs single electron transistor fabricated without modulation doping

We have fabricated a quantum dot single electron transistor, based on AlGaAs/GaAs heterojunction without modulation doping, which exhibits clear and stable Coulomb blockade oscillations. The temperature dependence of the Coulomb blockade peak line shape is well described by standard Coulomb blockade theory in the quantum regime. Bias spectroscopy measurements have allowed us to directly extract the charging energy, and showed clear evidence of excited state transport, confirming that individual quantum states in the dot can be resolved.