Temperature-Dependent Carrier Recombination and Efficiency Droop of AlGaN Deep Ultraviolet Light-Emitting Diodes

Abstract

We investigate temperature-dependent carrier transfer and efficiency droop on AlGaN-based deep ultraviolet light-emitting diodes. The Shockley-Read-Hall (SRH) recombination and carrier leakage are highly associated with the poor thermal stability. The existence of Auger recombination and carrier leakage is identified by the m-power method. A modified ABC model with an additional term f(n) related to carrier leakage is employed to analyze the evolution of multiple recombination mechanisms. The SRH process strongly suppresses both Auger recombination and carrier leakage at low currents. At high currents, the latter two processes are responsible for the efficiency droop and exhibit an anti-correlation upon temperature.

Perspectives on UVC LED: Its Progress and Application

“…They emit l high excitation densities, respectively, and thus, parasitic peaks that appe wavelength region can originate from different regions and different type tice defects [73]. The study of these parasitic peaks can determine the qua taxial layer of a device from one side and elucidate the mechanism of ca which provides a reference for the improvement of device epitaxy in the f tion, this group conducted research on the point-defect recombination in Shockley-Read-Hall recombination, trap-assisted recombination), leakage recombination, and other factors that affect the quantum efficiency [74] hand, Kneissl et al inferred that efficiency droop in AlGaN quantum-we tures are caused by an internal carrier loss process, analogous to what occu system. This loss process may be due to Auger recombination, where C = s −1 ; a similar value is commonly observed in InGaN-based devices [75].…”

“…The study of these parasitic peaks can determine the quality of the epitaxial layer of a device from one side and elucidate the mechanism of carrier transport, which provides a reference for the improvement of device epitaxy in the future. In addition, this group conducted research on the point-defect recombination in UV LED (i.e., Shockley-Read-Hall recombination, trap-assisted recombination), leakage current, Auger recombination, and other factors that affect the quantum efficiency [74]. On the other hand, Kneissl et al inferred that efficiency droop in AlGaN quantum-well heterostructures are caused by an internal carrier loss process, analogous to what occurs in an InGaN system.…”

“…These three mechanisms have been reported to reduce radiation recombination efficiency. Moreover, these three non-radiative recombination mechanisms change with temperature and excitation density, not only in terms of intensity, but also in terms of certain constraints between each other [74]. These methods can provide a reference for the effective operating current of a given device.…”

Very Low-Efficiency Droop in 293 nm AlGaN-Based Light-Emitting Diodes Featuring a Subtly Designed p-Type Layer

“…Zhang et al [ 25 ] reported a system in which the efficiency droop was approximately 4% at a current density of 110 A cm –2 , despite numerical calculations suggesting that it would almost be free of efficiency droop. Moreover, current droop (J-droop) and temperature droop (T-droop) processes, which are common with visible-light LEDs, are also severe problems in AlGaN-based UVB-LEDs, even for emission wavelengths of less than 280 nm [ 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 ]. In general, direct transitions between the conduction and valence bands are the key to enhancing the internal quantum efficiencies of multiple quantum wells (MQWs) when developing LEDs.…”

Size-Dependent Characterization of Deep UV Micro-Light-Emitting Diodes

“…In recent years, AlGaN-based LEDs which emit at ultraviolet (UV) wavelengths have begun to mature and have had a notable impact on several fields such as medicine, water purification, sensing and optical communications [1]. The benefit of using deep UV (DUV, UVB 280-315 nm, UVC 100-280 nm) for optical communications is that the ozone layer strongly absorbs most of this region of the electromagnetic spectrum; as a result, terrestrial DUV communications can operate in a low noise environment and can also be used in nonline of sight (NLOS) communications due to the substantial scattering of DUV light in air.…”