Temperature dependence of the electrical activity of localized defects in InGaN-based light emitting diodes

Abstract

Traps govern the temperature dependence of current in III-nitride quantum heterostructures, but frequently electrical measurements result unable to identify how many and what kind of defects take part in the conduction. The present work shows how a combined electrical and optical characterization in temperature can detect localized defects involved in injection mechanisms in InGaN/AlGaN/GaN blue light lmitting diodes. At least two different traps assisting the carrier injection by tunneling and playing an active role below and above 175 K, respectively, are identified in or nearby the active layers

Temperature and current dependence of the optical intensity and energy shift in blue InGaN-based light-emitting diodes: comparison between electroluminescence and cathodoluminescence

“…A role of the high driving voltage at low temperatures in promoting the carrier escape, mainly by tunnelling through the tilted potential barriers, must also be considered. From the I-V curves of the diodes [23] we determined indeed a strong increase of the voltage with decreasing temperature to keep a given current (e.g. at I = 0.5 mA, V goes from 2.91 V at RT to 4.75 V at 100 K) and the attainment of very large values (e.g.…”

“…If we evaluate the EL intensity of the QW peak as a function of the drive current at any given temperature, we have to deal with a very complex scenario [23]. However, a plain dependence turns out when the intensity is taken at T = T Intensity (L MAX ), as plotted in figure 5(b).…”

Implications of changes in the injection mechanisms on the low temperature electroluminescence in InGaN∕GaN light emitting diodes

“…As it was previously emphasized, 6 EL spectral measurements evidenced that only the SQW gives rise to blue radiative emission at about 2.72 eV, whereas it is reasonable to suppose that the ultraviolet MQW does not have high efficiency due to the very low hole density in this region. As it was previously emphasized, 6 EL spectral measurements evidenced that only the SQW gives rise to blue radiative emission at about 2.72 eV, whereas it is reasonable to suppose that the ultraviolet MQW does not have high efficiency due to the very low hole density in this region.…”

“…It is well known that not only the electrical features are highly affected by the above cited parameters, in particular, density, distribution, and nature of localized defects, [6][7][8][9] but also the optical efficiency. To our knowledge, few papers 10 mention the correlation between conduction processes, traps, and optical features.…”

A new approach to correlate transport processes and optical efficiency in GaN-based LEDs

“…Commercially available blue and green InGaN/AlGaN LEDs usually demonstrate good optical power, but the physical mechanisms responsible for both electrical conductivity and optical emission are still being intensively debated [1][2][3][4][5][6][7][8][9]. Works are in progress in order to get an exhaustive knowledge of the link between microscopic processes and macroscopic features and to obtain devices with better emission performance and reduced consumptions.…”