Improved GaN Quantum Well Microcavities for Robust Room Temperature Polaritonics

New experiments on state-of-the-art nitride polariton microcavities are reported which consist of high-quality 3?/2-membranes with 8, 10, or 3GaN/Al(0.07)Ga0.93N quantum wells, embedded in all-dielectric distributed Bragg reflectors (DBRs). The optical density of the membranes, extracted from transmittance measurements taking into account standing wave effects, is found proportional to the number of quantum wells. At room temperature, the optical density per quantum well at the exciton wavelength reaches values around 3.5%. It is demonstrated that a top DBR consisting of four alternating pairs of SiO2/Ta2O5 is sufficient to obtain robust polariton features from these membranes at room temperature, with a Rabi splitting of 36 and 71?meV for the 10 and 38 quantum well microcavities, respectively.