Resonantly probing micropillar cavity modes by photocurrent spectroscopy

We demonstrate electrical readout of high quality quantum dot micropillars by means of photocurrent (PC) spectroscopy under resonant excitation. Applying this technique enables a high spectral resolution mapping of the optical mode spectrum of the micropillar revealing quality factors of up to 11 000 for a 3 mu m diameter device. PC spectroscopy also shows that the contacted micropillars can act as light sensors with highly wavelength selective and photon sensitive detection capabilities down to 20 nW incident power. Moreover, bias voltage dependent PC studies provide an effective tool to study the competition between carrier tunneling out of the quantum dots and the radiative recombination.