GaAs photonic crystal slab nanocavities: Growth, fabrication, and quality factor

Progress in growth, fabrication, and characterization of semiconductor photonic crystal nanocavities

“…A 140 s dip in a KOH solution removed the debris, confirming that it was most likely a hydroxide of aluminum generated during the wet etch. The measured Qs of the cavities did improve noticeably following the removal of this debris, by an average of 50% on 10 different nanocavities, and the intensity of the photoluminescence also increased [7]. Such improvements in growth and fabrication have yielded modest improvements in the Qs we have been able to achieve.…”

“…We found, that even on samples where AFM showed a smooth surface, TEM images revealed that the top of the AlGaAs sacrificial layer could be very rough, with the roughness larger along one crystal axis. Changing certain MBE growth parameters reduced the roughness, but this did not result in a noticeable increase in Q [7], indicating that other loss mechanisms are still holding down the Qs. With future improvements in fabrication, we expect the smoothness of the AlGaAs layer to be significant.…”

“…We observe that the cavity Qs depend on polarization of the light in the fiber, of contact position on the nanobeam, and of angle between the nanobeam and the fiber [12]. We also present recent progress in the growth and fabrication of 2D photonic crystal slab nanocavities in GaAs with InAs QDs [6,7]. Fig.…”

“…Higher values of Q lead to longer photon lifetimes in the cavity (improved chance of light-matter interaction), and smaller values of V lead to higher field intensities (stronger light-matter interaction). The importance of the ratio Q/V can be seen in the expression for Purcell enhancement (F p / Q/V) of spontaneous emission and for vacuum Rabi splitting (VRS / Q/HV) [1,2,[5][6][7]. The pursuit of high Q, small V nanocavities has thus been a major focus of efforts in the semiconductor cavity QED community.…”

Characterization of 1D photonic crystal nanobeam cavities using curved microfiber

“…Decreasing V leads to higher field intensities in the cavity, and hence stronger interactions between the light and the matter. High Q and small V are pursued by the semiconductor cavity QED community because they are essential for large Purcell enhancement (F p  Q/V) of spontaneous emission and for a large vacuum Rabi splitting (VRS  Q/√V) [1,2,[4][5][6].…”