Photoreflectance spectroscopy of strained (In)GaAsN/GaAs multiple quantum wells

Abstract

The effect of a variation of the indium and nitrogen concentrations in InxGa1−xAs1−yNy/GaAs multiquantum wells grown by molecular beam epitaxy is studied systematically by room temperature photoreflectance spectroscopy. The band gap redshift caused by a nitrogen fraction of 1.5% decreases by as much as 30% as the indium fraction increases from 0% to 20%. A moderate increase of electron effective mass (Δme∼0.03 m0) is found in all samples containing nitrogen (y≳1%). In compressively strained quantum wells, the energy separation between the first confined heavy and light hole energy levels decreases in a regular manner as the nitrogen fraction increases from 0% to 1.7%, suggesting that the modification of the valence bands due to nitrogen incorporation can be explained by the strain variation.