A study of the inclusion of prelayers in InGaN/GaN single‐ and multiple‐quantum‐well structures

Abstract

We report on the effects on the optical properties of blue‐light emitting InGaN/GaN single‐ and multiple‐quantum‐well structures including a variety of prelayers. For each single‐quantum‐well structure containing a Si‐doped prelayer, we measured a large blue shift of the photoluminescence peak energy and a significant increase in radiative recombination rate at 10 K. Calculations of the conduction and valence band energies show a strong reduction in the built‐in electric field across the quantum well (QW) occurs when including Si‐doped prelayers, due to enhancement of the surface polarization field which opposes the built‐in field. The reduction in built‐in field across the QW results in an increase in the electron–hole wavefunction overlap, increasing the radiative recombination rate, and a reduction in the strength of the quantum confined Stark effect, leading to the observed blue shift of the emission peak. The largest reduction of the built‐in field occurred for an InGaN:Si prelayer, in which the additional InGaN/GaN interface of the prelayer, in close proximity to the QW, was shown to further reduce the built‐in field. Study of multiple QW structures with and without an InGaN:Si prelayer showed the same mechanisms identified in the equivalent single‐quantum‐well structure.