Probing the Dark-Exciton States of a Single Quantum Dot Using Photocurrent Spectroscopy in a Magnetic Field

Abstract

We report on high-resolution photoluminescence (PL) and photocurrent (PC) spectroscopies of a single self-assembled InAs/GaAs quantum dot (QD) embedded in an n-i-Schottky device with an applied magnetic field in Faraday and Voigt geometries. The single-QD PC spectrum of neutral exciton (X 0 ) is obtained by sweeping the bias-dependent X 0 transition energy to achieve resonance with a fixed narrow-bandwidth laser through quantum-confined Stark effect. With a magnetic field applied in Faraday geometry, the diamagnetic effect and the Zeeman splitting of X 0 are observed both in PL and PC spectra. When the magnetic field is applied in Voigt geometry, the mixture of bright and dark states results in an observation of dark exciton states, which are confirmed by the polarization-resolved PL and PC spectra.

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

“…that because of the fixed energy of the pumping laser, the energy level of X + is tuned lower to match the laser energy with an additional energy shift induced by the diamagnetic effect and the Zeeman splitting. As a result, the peaks of the PC spectra move to the negative bias voltage (high electric field) direction at a high magnetic field [50]. Here, due to the giant PC enhancement of X + caused by the reuse of hole state is destroyed by the magnetic field, the PC amplitudes in Fig.…”

Strong Triplet-Exciton–LO-Phonon Coupling in Two-Dimensional Layered Organic–Inorganic Hybrid Perovskite Single Crystal Microflakes

“…33 This further excludes the possibility that P2 comes from biexcitons whose dependence coefficient of PL intensity on excitation power should be around 2. 18,24,34,35 Figure 3c displays the normalized PL spectra as a function of temperature of the sample 1. When the temperature is lower than 39.8 K, the P1 peak shows a slight blue shift with an increase in exciton peak energy by about 2.54 meV as the temperature increases.…”

Dark-bright exciton coupling in asymmetric quantum dots

“…Alternatively, applying a transverse magnetic field (Voigt geometry) leads to a mixing between the bright and dark states, resulting in the appearance of two DE branches in addition to the two BE branches in magnetoluminescence spectra. These spectra allow the determination of the DB splitting DB and the DE fine-structure splitting 2 [14] (Fig. 1).…”