Injection characteristics of polar and nonpolar multiple‐QW structures and active region ballistic overshoot

Electron ballistic overshoot of the active region is shown to dominate the leakage current in light-emitting III-nitride multi-QW diode structures. At high injection levels typical for laser diodes, the overshoot-assisted leakage is comparable in polar and nonpolar structures whilst in the low injection LED regime nonpolar structures reveal much smaller leakage; this complies with available observations of LED efficiency droop. We show that drift-diffusion approximation for electron transport noticeably underestimates the leakage, especially in nonpolar structures. Ballistic spill-over also increases the electron concentration in p -side waveguide layers and enhances the nonradiative recombination loss. (© 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)