Influence of the deposition time of barrier layers on optical and structural properties of high-efficiency green-light-emitting InGaN∕GaN multiple quantum wells

Abstract

We reported the effect of the deposition time of barrier layers on optical and structural properties of high-efficiency green-light-emitting InGaN∕GaN multiple quantum wells (MQWs) by photoluminescence (PL) and high-resolution x-ray diffraction techniques. The MQW samples on (0001)-plane sapphire substrates were prepared with a ramping method by metalorganic chemical deposition. It was found that the structural or interface quality of the MQW system improved as the deposition time of barrier layers increased from 10 to 14min, but lattice relaxation was still observed. The relaxation degree decreases from 33% to 6% as the deposition time increases. Temperature-dependent PL measurements from 12 to 300K indicated that the integrated PL intensities start to decay rapidly as temperature rises above 50K for the sample with the shorter deposition time, and above 100K for the sample with the longer deposition time. The luminescence thermal quenching of the two samples suggests the two nonradiative recombination centers based on a fit to Arrhenius plot of the normalized integrated PL intensity over the entire temperature range. The first centers at higher temperatures show less difference for the two samples. The second centers at lower temperatures can be attributed to the trapping of carriers at the rough interface for the sample with the shorter deposition time and to the thermal quenching of bound excitons for the sample with the longer deposition time, respectively.

Temperature-dependent photoluminescence in light-emitting diodes

“…3(a). The temperature-dependent PL intensity can be well fitted using the following Arrhenius formula3243444546: where I(T) represents the normalized integrated PL intensity. The parameters C 1 and C 2 are two constants related to the density of non-radiative recombination centres in the samples.…”

“…The parameters C 1 and C 2 are two constants related to the density of non-radiative recombination centres in the samples. E A1 and E A2 are the activation energies corresponding to the non-radiative recombination process45464748. k B is Boltzmann's constant.…”

Blue and green emission using In(Ga)N/GaN quantum wells with InN well layers grown by metalorganic chemical vapor deposition

“…It is presumed that a slight increase in E H in sample C is related to the formation of stacking faults and the bending of lattice fringes due to increased misfit strain. On the other hand, it has been reported that E L values in the low temperature range are dominated by the degree of carrier localization captured in the potential minima [26]. Sample A with a very thin well-width, had a much larger activation energy than thermal energy kT when T was 80 K ($7 meV).…”

“…In particular, the integrated PL intensity of sample A decreased less rapidly in the temperature range 50-100 K. To achieve best-fit, we applied PL results to Eq. (1) using two activation energies [26], E L and E H , corresponding to two different nonradiative-recombination mechanisms at low and high temperature ranges, respectively.…”

Strain variation in p-GaN by different spacer layers in the light emitting diodes and their microstructural and emission behaviors

“…Currently, the main issue related to the LEDs fabrication is to realize the white color emitters based on high-brightness blue and ultraviolet LEDs through improvements in the emission efficiency of visible LEDs [2]. For it, we have to reduce the dislocation density in nitride films and improve the electrical properties of the p-type contact layer doped with commonly used Mg atoms [3].…”