Anneal-induced interdiffusion in 1.3-μm GaInNAs/GaAs quantum well structures grown by molecular-beam epitaxy

Abstract

High-resolution x-ray diffraction (HRXRD) and photoluminescence (PL) have been used to study the diffusion of atoms in 8-nm Ga0.628 In0.372 N0.015 As0. 985 GaAs quantum well, with and without dielectric encapsulants. These samples were repeatedly annealed in the temperature range of 680-800 °C over times of up to 16 000 s. HRXRD simulations, by using dynamic scattering theory and Fick's diffusion model with a constant diffusion coefficient, demonstrate that the diffusion lengths are shorter than 2 nm under the annealing conditions studied. In this range of diffusion lengths, the transition energy Ee1-Hh1, numerically calculated from the Schrödinger equation using a potential derived from the diffusion equation, increases linearly as the square of the diffusion length. The steady-state PL blueshifts, after a fast initial blueshift due to the rearrangement of local nitrogen bonding configurations N- Gam In4-m (0≤m≤4), otherwise known as short-range order, as a function of annealing time are well fitted by using the linear function. The values of Δ ESRO and diffusion coefficients obtained are 18-28 meV and 3.0× 10-20 -3.5× 10-18 cm2 s, respectively. The activation energy characterized from the diffusion coefficients at different temperatures is 3.25 eV and is not affected by the dielectric encapsulates. © 2006 American Institute of Physics.