Impact of surface recombination on efficiency of III‐nitride light‐emitting diodes

Abstract

The paper considers surface recombination at the free active region surface as the mechanism of carrier losses which has not yet been discussed with regard to III‐nitride LEDs despite of its evident importance for AlGaInP‐based light emitters. Using advanced thin‐film and triangular volumetric chip designs reported in literature as prototypes, we have demonstrated by simulation a noticeable impact of surface recombination on the wall‐plug efficiency of InGaN‐based LEDs. Various types of LEDs whose efficiency may be especially affected by surface recombination are discussed. (© 2016 WILEY‐VCH Verlag GmbH &Co. KGaA, Weinheim)

Effect of Die Shape and Size on Performance of III-Nitride Micro-LEDs: A Modeling Study

“…On the other hand, the use of small angles, θ, of the facet inclination, which is beneficial for high LEE, may alter the surface recombination velocity. Indirect evidence for this is a large scatter in the data on V S in InGaN and GaN, reported for various crystal orientations (see [21] for a more detailed literature review on this issue). Therefore, experimental investigations into the crystal orientation dependence of surface recombination velocity are quite desirable for future developments of µ-LEDs.…”

“…Surface recombination is accounted for in our simulations via boundary conditions for 2D carrier transport equations in the LED active region [21]. As it was mentioned previously [21], the surface recombination velocity V S is known for InGaN materials with insufficient accuracy. In order to evaluate its value more accurately, we used the recent data [22] on the size-dependent effective SRH recombination coefficient A', which is related to the perimeter (1) and shows the parameters j S , ρ S , and m extracted from the fitting.…”

“…Surface recombination is accounted for in our simulations via boundary conditions for 2D carr transport equations in the LED active region [21]. As it was mentioned previously [21], the surfa recombination velocity V S is known for InGaN materials with insufficient accuracy.…”

“…Surface recombination is accounted for in our simulations via boundary conditions for 2D carr transport equations in the LED active region [21]. As it was mentioned previously [21], the surfa recombination velocity V S is known for InGaN materials with insufficient accuracy. In order evaluate its value more accurately, we used the recent data [22] on the size-dependent effective SR recombination coefficient A', which is related to the perimeter P and area Σ of the LED active regio via an approximate equation valid for sufficiently small devices [10,23]: 1 evaluate its value more accurately, we used the recent data [22] on the size-dependent effective SRH recombination coefficient A', which is related to the perimeter P and area Σ of the LED active region, via an approximate equation valid for sufficiently small devices [10,23]: Approximating the data of [22] by the above expression (see Figure 3), we have obtained V S = 7.5 × 10 3 cm/s.…”

From Large‐Size to Micro‐LEDs: Scaling Trends Revealed by Modeling

“…This can be explained by shortening of non-equilibrium carrier life time in the active region and subsequent decrease of their ambipolar diffusion length which controls the "dead" areas at the active region edges (see Figure 4b,c) where surface recombination is valuable. [7] The second tendency is decrease in the surface-recombination losses with the LED chip size, which is expectable because of the ratio of the above "dead" area to the total area of the active region decreasing with the chip dimensions.…”