Deterministic placement of quantum defects in arrays of 4H-SiC micropillars

Silicon carbide (SiC) is a very promising material for the fabrication of single photon sources, quantum bits and nanoscale sensors of magnetic and electric fields, pressure or temperature. These quantum applications are possible thanks to several atomic defects (color centers) which have very favorable optical and spin properties.
For many applications, a high collection efficiency of the emitted light is a crucial issue for the use at room temperature (RT). As most of the defects emit in the NIR, there is also a need to improve their spontaneous emission at RT.
In this work we focus on the enhancement of the emission of the following defects in 4H-SiC : VSi (Si vacancy – zero phonon line (ZPL) at 862 nm and 917 nm), VSi-VC (di-vacancy – ZPL at 1079 nm and 1131 nm), NCVSi (NV center, ZPL at 1180 nm, 1223 nm and 1242 nm). Towards this end, we develop a scalable array of micropillars incorporating the defects readily available for efficient interfacing with free space objective and lensed fibers.
Micropillars are fabricated by inductively coupled plasma RIE on commercial n-type4H-SiC. Using UV laser lithography and a metallic hard mask (Ti/Ni) we realize micropillars array with height of 4.5 µm, diameter of 700 nm and a pitch of 4 µm. The samples are then irradiated at RT with 300 keV H+ to create point defects. This gives a maximum concentration at 2 µm under the sample surface. Annealing at different temperature under neutral N2 atmosphere is used to promote the defects presence (VSi without annealing, 750°C for VSiVC, 900°C for NCVSi).
We obtained an enhancement factor of 20 for the VSi and 7 for the VSiVc.

Left : MEB image of the micro-pillars array.
Right : Room temperature micro-phototluminescence cartographie of the Vsi defect.

Contacts:

Pr. Jean-Marie Bluet

Team Nanomatériaux Fonctionnels

References and collaborations:

Deterministic placement of ultra-bright near infrared color centers in arrays of silicon carbide micropillars.
S. Casteletto, A. S. Al Atem, F. A. Inam, H. J. Von Bardeleben, S. Hameau, A. F. Almutairi, G. Guillot, S. Sato, A. Boretti and J. M. Bluet
Bellstein J. Nanotechnol. 2019, 10, 2383-2395.
DOI : 10.3762/bjnano.10.229

Collaboration with RMIT, Melbourne, Australia.