Electron and Hole g Tensors of Neutral and Charged Excitons in Single Quantum Dots by High-Resolution Photocurrent Spectroscopy

We report high-resolution photocurrent (PC) spectroscopy of a single self-assembled InAs/GaAs quantum dot embedded in an n-i Schottky device in an applied vector magnetic field. The PC spectra of positively charged excitons (X+) and neutral excitons (X-0) are obtained by two-color resonant excitation. With an applied magnetic field in the Voigt geometry, the double-Lambda energy-level structure of X+ and the dark states of X-0 are observed clearly in the PC spectra. In the Faraday geometry, the PC amplitude of X+ decreases and is then quenched with increasing magnetic field, which provides a new way to determine the relative sign of the electron and hole g-factors. With an applied vector magnetic field, the electron and hole g-factor tensors of X+ and X-0 are obtained. The anisotropy of the hole g-factors of both X+ and X-0 is larger than that of the electron g-factors.