Nanoplasmonic Enhancement of Semiconductor Quantum Emitters

摘要

Semiconductor quantum dots (QDs) are excellent candidates for single photon quantum emission applications, due to their excellent stability, narrow spectral linewidth and nanosecond scale radiative lifetime [1]. A strong advantage of this platform over competing technologies is the possibility to benefit of the accurate control of the photonic environment, offered by advanced nanophotonics fabrication techniques. For example, QDs can be embedded in nanopillars, nanowires (NWs), microdiscs or more exotic nano-structures, to enhance the efficiency of the emission [1]-[4]. Additionally, these micro- and nano-cavities can be further decorated with complex nanoplasmonic structures, to increase, optimize and ultimately control their emission properties[2]. However, most nanolithographic techniques require a number of complex fabrication steps, to align carefully the metallic features to the semiconductor geometries. This difficulty is exacerbated if the QDs are distributed randomly in a substrate. Here, we demonstrate a direct writing approach to create metallic nanostructures on semiconductor NWs, resorting to the electron-beam-induced deposition (EBID) method [5]. EBID uses focused electron beam (FEB) to reduce gas precursors injected locally in proximity of the sample. The quality of the deposited materials depends on the gas flow, temperature, the scanning speed of the FEB and its energy. This approach permits to create three-dimensional patterns with nanometric resolution and positional accuracy and does not need wet lithographic steps.