Spectral shape and broadening of emission from AlGaInP light-emitting diodes

Abstract

Articles you may be interested inSelf-heating and athermal effects on the electroluminescence spectral modulation of an AlGaInP light-emitting diode J. Appl. Phys. 110, 073103 (2011); 10.1063/1.3643005 Effects of In composition on ultraviolet emission efficiency in quaternary InAlGaN light-emitting diodes on freestanding GaN substrates and sapphire substrates J. Appl. Phys. 98, 113514 (2005); 10.1063/1.2134885 Experimental determination of the internal quantum efficiency of AlGaInP microcavity light-emitting diodes Erratum: "Evidence of localization effects in InGaN single-quantum-well ultraviolet light-emitting diodes" [Appl.This work presents a model for describing the shape of the spontaneous emission spectrum from a quantum-well structure. A function is introduced to specify the probability distribution for the effective band gap. Based on this model, the coexisting carrier thermal broadening and effective band gap broadening in the spontaneous emission spectrum can be separated from each other. Applying this model to the spectra of AlGaInP light-emitting diodes reveals that the probability distribution functions are almost Gaussian. Therefore, the emission spectra can be described by an analytical expression with fitted parameters. Possible reasons for this band gap broadening are discussed. The determination of the junction temperatures from the emission spectra and possible deviations of the results thus determined are also elaborated.

Measuring Thermally-Driven LED Emissions via Voltage Modulation near Zero Bias

“…We find a carrier recombination temperature which is not consistent with the junction temperature, particularly at higher junction temperatures [6][7][8][9][10][11][12]. This effect is larger than previously noted [10,13]. The spectrum near 0 V suggests a violation of Kirchhoff's Law.…”

Modeling the spectral shape of InGaAlP-based red light-emitting diodes

“…The spectrum is a product of the joint density of states (DOS) of electrons and holes, with the highest contribution to the low energy wing of the spectrum, and the Maxwell-Boltzmann distribution dominating the high energy wing of the spectrum. 5,6 For bulk LEDs, the ideal three-dimensional DOS follows the free electron model with parabolic shape, whereas for quantum-well (QW) LEDs each sub-band of the ideal two-dimensional DOS produces a step function. 5,6 Modern commercial high-power LEDs have a QW structure to achieve higher radiative recombination rate.…”

Temperature invariant energy value in LED spectra

“…The real spectra of quantum-well LEDs do not rise sharply as the stepwise joint density of states predicts, but the spectra are broadened. 16 The difference between the model and the measured spectrum is due to subbandgap recombination which affects the low-energy side of the spectrum. 5 Equation (1) is thus valid only on the highenergy side of the spectrum.…”

“…In quantum well LEDs, the densities of states of the carriers are theoretically derived to be step functions. However, the measured joint density of states follows a broadened, rounded step function 16 with an unknown detailed shape. For LEDs manufactured using bulk, direct band gap semiconductors, the theoretical joint density of states follows the square root ½E À E g ðTÞ 1=2 , 16 but here we allow any energy dependence for the density of states f ðE À E g ðTÞÞ.…”

“…1, 15,16 The emission intensity of an LED is proportional to the product of the joint density of states f and the exponential Boltzmann distribution of carriers…”