Micrometer scale InGaN green light emitting diodes with ultra-stable operation

Abstract

We report on the demonstration of InGaN photonic nanocrystal light emitting diodes (LEDs), which operate in the green wavelength (∼548 nm). The devices are designed to operate at the Γ point of the photonic band structure and exhibit a spectral linewidth ∼4 nm, which is nearly five to ten times narrower than that of conventional InGaN quantum well LEDs in this wavelength range. Significantly, the device performance, in terms of the emission peak and spectral linewidth, is nearly invariant with injection current, suggesting the insusceptibility to quantum-confined Stark effect commonly seen in InGaN quantum wells. The external quantum efficiency is characterized by a sharp rise with increasing current and reaches a maximum at ∼5 A/cm2, which is comparable to conventional blue quantum well LEDs. A relatively small (∼30%) efficiency droop was measured at an injection current density over 200 A/cm2 at room temperature without any active cooling.