Analytic model for the efficiency droop in semiconductors with asymmetric carrier-transport properties based on drift-induced reduction of injection efficiency

Abstract

An analytic model is developed for the droop in the efficiency-versus-current curve for light-emitting diodes (LEDs) made from semiconductors having strong asymmetry in carrier concentration and mobility. For pn-junction diodes made of such semiconductors, the high-injection condition is generalized to include mobilities. Under high-injection conditions, electron drift in the p-type layer causes a reduction in injection efficiency. The drift-induced leakage term is shown to have a 3rd and 4th power dependence on the carrier concentration in the active region; the values of the 3rd-and 4th-order coefficients are derived. The model is suited to explain experimental efficiency-versus-current curves of LEDs. V C 2012 American Institute of Physics. [http://dx.

Influence of electron distribution on efficiency droop for GaN-based light emitting diodes

“…where the high power term f(n) is the electron overflow term [13,14]. If taking the carrier localization into account as well, the effective volume of the active region will be introduced [15,16], and compared with the conventional ABC model, the corrected ABC model will exhibit better fitting to the experimental results.…”

Overshoot effects of electron on efficiency droop in InGaN/GaN MQW light-emitting diodes

“…To date, research on carrier leakage of InGaN/GaN LEDs are scattered in experiment and theory, 6,8,11,15 …”

“…1,2 Although many theories have attempted to explain these experimental observations, including device heating, 3 delocalization of carriers, 4 Auger recombination, 5 and electron leakage, 6 there is still no consensus on their underlying physical mechanism. Electron leakage is commonly regarded as having an important contribution to the remarkable efficiency loss, especially at high injected current.…”

“…Electron leakage is commonly regarded as having an important contribution to the remarkable efficiency loss, especially at high injected current. Such leakage is caused by poor hole-injection efficiency, 6 an ineffective electron blocking layer (EBL), 7,8 non-capture of electrons by quantum wells (QWs), 9 and electron escape from the QWs. 10 Recently, ballistic and quasi-ballistic transport in electron leakage was investigated for InGaN/GaN LEDs with single double heterostructure (DH) active regions, producing a good agreement with experiments.…”

Effect of InGaN thickness on assisted trap recombination and behaviour of InGaN/AlGaN double heterostructure LED

“…Besides that, the carrier injection efficiency has the key functions in the light emission efficiency of GaN based LEDs. Meeyard et al [8,9] reported asymmetry during carrier transport because of the much lower concentration and mobility of holes in p-GaN and p-AlGaN compared with electrons. The asymmetry in carrier transport reduces the light emission efficiency of LEDs and enlarges the efficiency droop.…”