Semipolar InGaN/GaN Converters for Bright Green Emission and Stripe LEDs 59 Semipolar InGaN/GaN Converters for Bright Green Emission and Stripe Light Emitting Diodes

Optically pumped green converter structures based on three-dimensional (3D) inverse pyramids were studied. The green emission intensity is determined by the conversion rate ηc and the absorption fraction ηa, indicating the InGaN/GaN quantum well (QW) crystal quality and its absorption capability, respectively. 15 was found to be the optimal QW number based the epitaxial condition for that series of green converters while a smaller number decreases ηa and a larger number degrades the QW quality and then decreases ηc. The thermal budget was found to be a critical issue for the InGaN/GaN QWs with a high indium content. A low InGaN growth temperature is required to achieve green emission leading to an inferior InGaN quality. A larger thickness, a higher TMIn molar flow and a higher reactor pressure are helpful to increase the InGaN well growth temperature for a certain emission wavelength. However, the higher reactor pressure results in worse InGaN quality finally. Conventional light emitting diodes (LEDs) based on 3D stripes were also investigated. The leakage current is related to the local high density defects generated within the active region penetrating the p-GaN, probably at the apex. It was successfully suppressed by reducing the QW number from 5 to 1 and inserting an AlGaN layer in the p-side of the structures in some distance to the QWs.