Piezoelectric effects in the optical properties of strained InGaN quantum wells

We investigated the carrier-injection effects in the emission spectrum of strained GaN/InGaN/AlGaN quantum well (QW) blue emitters using a pulsed current excitation technique. Spectral blueshift as large as 80 meV in the emission peak energy was observed as the injection current increases from 1 mA to 1 A. Based on a self-consistent calculation that couples the Poisson equation with a wurtzite-type Rashba–Sheka–Pikus Hamiltonian, four important interactions are evaluated in order to determine the optical properties of InGaN QW. It is shown that the spectral redshifting caused by a piezoelectricity induced quantum confined Stark effect and carrier-induced band gap renormalization is counteracted by a blueshift due to the band filling and charge screening effects. The increase of InGaN QW emission peak energy and intensity with injected carriers suggests a dominant contribution from the latter in a band-to-band recombination process.