InGaN quantum wells (thin InGaN layers sandwiched in GaN) are the active light-emitting region of virtually all commercial blue and green LEDs and laser diodes, which in turn are the basis of white LEDs (blue LED + phosphor). The blue InGaN LED — commercialised by Shuji Nakamura and colleagues in the 1990s, Nobel Prize in Physics 2014 — is the most important efficiency gain in lighting in a century. Red InGaN LEDs at high indium content (~40%) are an active research frontier, motivated by micro-LED display applications.
The central materials challenge is indium inhomogeneity: indium atoms have a much larger atomic radius than gallium, and the two-element system phase-separates during MOCVD growth, creating composition fluctuations. These fluctuations are both a liability (non-uniform emission, efficiency droop at high carrier density) and — paradoxically — a partial efficiency asset at low carrier densities (carriers localise in indium-rich quantum dots that reduce non-radiative recombination). Understanding and controlling this mechanism is an active research area.
InGaN micro-LEDs are a priority technology for AR/VR display panels, where their brightness and efficiency advantages over OLEDs matter at small pixel sizes (<10 μm). Gallium Nitride is the structural parent material; Aluminium Gallium Nitride covers the complementary UV side of the nitride alloy family.
Frontier
- Can micro-LED displays using InGaN reach the luminous efficiency and pixel-level uniformity needed for mass-market AR glasses before oxide-TFT backplane costs make them viable?
- Does InGaN’s anomalously high efficiency at low carrier density fully yield to V-pit and strain engineering, or does indium segregation remain a fundamental ceiling?
- Will InGaN-based tandem solar cells (stacked with Si) break the single-junction Shockley–Queisser limit in production, making them competitive with III-V multi-junction cells at a fraction of the cost?