Narrow optical linewidths and spin pumping on charge-tunable close-to-surface self-assembled quantum dots in an ultrathin diode

Quantum dots in photonic crystal membrane structures are an attractive platform for on-chip quantum photonics. However, charge control of quantum dots in thin membranes is challenging. The widely used p-i-n diodes operate typically at high bias, resulting in high leakage currents. Here, a modified diode design is presented, fully compatible with the fabrication of photonic crystals, that enables deterministic charging of embedded quantum dots at small biases and, hence, small currents. Narrow optical linewidths and optical spin pumping are demonstrated on quantum dots in this ultrathin diode structure.