Direct determination of the piezoelectric field in (111) strained InGaAs/GaAs multiple quantum well p-i-n structures by photoreflectance

The photoreflectance (PR) technique has been applied to a p-i-n structure at room temperature containing InGaAs/GaAs multiple quantum wells to directly obtain the strain induced piezoelectric held and other critical parameters of the structure which was grown by molecular beam epitaxy on a (111)B GaAs substrate. It is shown that by this technique it is possible to measure the barrier held in the intrinsic regions of the diode through the Franz-Keldysh effect as well as the optical transition energies between all the confined electron and hole states in the wells. Structural parameters such as the well and barrier widths, length of the intrinsic region and InGaAs composition were determined from high-resolution X-ray diffractometry. As the p-i-n diode has a well defined built-in potential, by using this value in conjunction with a comprehensive characterization of the sample it is then possible to determine accurately the piezoelectric field in the wells. The measured value is compared to previously reported values. 1998 Published by Elsevier Science B.V. All rights reserved.