Search

We report on photocurrent and photoconductance processes in a freely suspended p-doped single GaAs nanowire. The nanowires are grown by molecular beam epitaxy (MBE), and they are electrically contacted by a focused ion beam (FIB) deposition technique. The observed photocurrent is generated at the Schottky contacts between the nanowire and metal source-drain electrodes, while the observed photoconductance signal can be explained by a photogating effect induced by optically generated charge carriers located at the surface of the nanowire. Both optoelectronic effects are sensitive to the polarization of the exciting laser field, enabling polarization dependent photodetectors.

In this invited paper of the 28th International Conference of the Physics of Semiconductors (ICPS-28), we discuss the peculiar quantum electrodynamical properties of a semiconductor microcavity system, in which a cavity photon mode is strongly coupled to an intersubband transition of a doped quantum well system. In this kind of semiconductor system, it is possible to achieve an unprecedented ultrastrong coupling regime, in which the vacuum Rabi frequency is comparable to the electronic transition frequency. We discuss the anomalous quantum properties of the quantum ground state (a squeezed vacuum) and of the intersubband cavity polariton excitations. We address the role of dissipation and point out some future perspectives concerning the investigation of quantum vacuum radiation effects induced by an ultrafast time modulation of the quantum vacuum.