Effect of composition‐graded interlayers in double‐heterostructure blue InGaN light‐emitting diodes

Abstract

The optical and electrical characteristics of the double‐heterostructure (DH) blue InGaN light‐emitting diodes (LEDs) with composition‐graded interlayers are studied numerically. Specifically, the detailed physical mechanisms and influences of grading layer thickness on the LED performance are explored systematically. Simulation results reveal that besides the advantages of mitigating lattice relaxation in real epitaxy, the employment of thick composition‐graded interlayers can benefit from the enhanced spatial separation of electron–hole wavefunctions, suppressed Auger recombination, and reduced polarization effect in DH active region. The illumination efficiency and electrical characteristics are markedly improved when the thick grading layers are employed.

Electron mobility in abrupt-interface and step-graded AlGaN/GaN Heterostructures

“…Experimental studies [6] showed that dislocation density could be reduced significantly by using linearly graded and step-graded AlGaN layers. A numerical study [7] also found the graded barrier layer could result in enhanced electron injection and confinement in double-heterostructure InGaN LEDs. On the other hand, the interface shape can affect the crossing of wave function envelops into the barrier layer, which changes the alloy disorder scattering and interface roughness scattering.…”

Investigation of the Structural and Optical Properties of Compositionally V‐Graded Strained InxGa1–xN Layers

“…For example, in metal‐organic vapor phase epitaxy (MOVPE) step‐graded interlayers were shown to reduce the dislocation density of subsequent layers . Compositionally graded InGaN layers have also been shown to have an effect on the internal quantum efficiency improvement in double heterojunction blue light‐emitting diodes (LEDs) . Finally, it has been shown that thick, low‐temperature growth of compositionally graded InGaN helps to reduce defect formation and facilitates growth within the miscibility gap …”

“…[11] Compositionally graded InGaN layers have also been shown to have an effect on the internal quantum efficiency improvement in double heterojunction blue light-emitting diodes (LEDs). [12] Finally, it has been shown that thick, low-temperature growth of compositionally graded InGaN helps to reduce defect formation and facilitates growth within the miscibility gap. [13] However, high indium composition material still needs more attention.…”

Improving GaN-based light-emitting diodes

“…where C is the Auger coefficient. Typical value of the Auger coefficient is from 10 -28 -10 -29 cm 6 /s for III-nitride semiconductors [38][39][40][41][42].…”