Photocurrent and photoluminescence of a single self-assembled quantum dot in electric fields

Abstract

We have fabricated single-quantum-dot photodiodes by embedding InGaAs quantum dots in the intrinsic region of an n-i-Schottky diode combined with near-field shadow masks. As a function of the bias voltage, we study one and the same quantum dot in the two complementary regimes of photocurrent and photoluminescence. The Stark shift of the excitonground state continues monotonically in both regimes, confirming nicely the observation of the same quantum dot in photoluminescence and photocurrent. In the limit of high electric fields, we observe a broadening of the photocurrentlinewidth from which we determine a strongly reduced exciton lifetime of below 1 ps.