Room temperature luminescence of passivated InGaN quantum dots formed by quantum-sized-controlled photoelectrochemical etching

Abstract

Room temperature luminescence of epitaxial InGaN quantum dots (QDs) formed by quantum sized-controlled photoelectrochemical (QSC-PEC) etching and passivation layer regrowth is demonstrated. QSC-PEC etching is performed on a 7.5 nm thick In0.20Ga0.80N layer emitting at ∼514–521 nm and with a laser diode emitting at 445 nm. Parameters such as etch bias (0.9 V and 1.5 V), laser average power (20 mW/cm2 and 100 mW/cm2), and laser operating conditions (pulsed and continuous wave) are explored. QSC-PEC etching of In0.20Ga0.80N requires a minimum bias (>0.9 V) and pulsed laser conditions in order to form QDs. After etching, the QDs do not exhibit photoluminescence due to defect recombination. Regrowth of passivation layers consisting of a 2 nm thick Al0.45Ga0.55N layer and a 11 nm thick GaN layer reduce the defect recombination, and room temperature photoluminescence is observed at room temperature at ∼435–445 nm with narrow full-width at half-maximum of ∼35 nm.