Carrier leakage in InGaN quantum well light-emitting diodes emitting at 480 nm

Abstract

Pulsed light-current characteristics of InGaN/GaN quantum well light-emitting diodes have been measured as a function of temperature, with sublinear behavior observed over the whole temperature range, 130-330 K. A distinctive temperature dependence is also noted where the light output, at a fixed current, initially increases with temperature, before reaching a maximum at 250 K and then decreases with subsequent increases in temperature. On the basis of a drift diffusion model, we can explain the sublinear light-current characteristics and the temperature dependence by the influence of the large acceptor ionization energy in Mg-doped GaN together with a triangular density of states function characteristic of localized states. Without the incorporation of localization effects, we are unable to reproduce the temperature dependence whilst maintaining emission at the observed wavelength. This highlights the importance of localization effects on device performance.

Defect recombination induced by density-activated carrier diffusion in nonpolar InGaN quantum wells

“…[1][2][3] In the past decade, multiple mechanisms have been proposed to explain the efficiency droop including Auger recombination induced by multi-particle interactions, [4][5][6][7][8] electron leakage due to poor hole injection and electron overflow, 9,10 carrier loss related to reduction or saturation of carrier localization, 11,12 and other processes including the density-activated defect recombination (DADR). 13,14 Some of these factors have been found to be tightly associated with the internal polarization field.…”

Comparative studies of efficiency droop in polar and non-polar InGaN quantum wells

“…Efficiency droop, the reduction in the efficiency of light emitting diodes at high drive currents, is one of the most serious problems in the use of nitride Light emitting diodes (LEDs) for high brightness applications. 9,10 Several mechanisms have been put forward to explain droop, including problems with hole injection, 10,11 Auger recombination, 12,13 carrier escape, 14 and non-radiative recombination following the saturation of localised states. [15][16][17] There are now a number of publications suggesting that non-polar InGaN QWs may be less susceptible to efficiency droop than c-plane structures and a range of explanations have been put forward to explain these observations.…”

Room temperature PL efficiency of InGaN/GaN quantum well structures with prelayers as a function of number of quantum wells

“…One source of efficiency loss in InGaN/GaN QW structures and LEDs is the thermal escape of carriers from the QW confining potential before they recombine [21,22]. The RT IQE of InGaN/GaN MQW structures, and LEDs, without prelayers has been measured to increase with increasing number of QWs, an effect which has been attributed to the recapture of carriers by adjacent QWs [23,24].…”