Internal efficiency of LEDs: An application of Quantum Mechanics.
Résumé
Modern LEDs are based on nanometric semiconductor structures such as quantum wells or quantum dots. Playing with their composition and sizes, we can adjust the light emission wavelength, while improving the radiative efficiency. We will explain how the knowledge of quantum mechanics allows us to tailor the optical properties of these light-emitting systems. We will focus specifically on the case of nanostructures based on group III nitride semiconductors (GaN, InGaN, AlGaN). These materials indeed permit to emit light covering the entire visible spectrum and they therefore emerged in the last decade as systems of choice for applications such as domestic lighting, automotive headlights,... We will discuss the practical limitations of performances encountered with these materials and how these limitations can be suppressed, thanks -again- to an appropriate application of quantum mechanics.