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 struct ure at room temperature containing InGaAs/GaAs multiple quantum wells to directly obtain the strain induced piezoelectric held and other cri tical parameters of the structure which was grown by molecular beam ep itaxy on a (111)B GaAs substrate. It is shown that by this technique i t is possible to measure the barrier held in the intrinsic regions of the diode through the Franz-Keldysh effect as well as the optical tran sition energies between all the confined electron and hole states in t he wells. Structural parameters such as the well and barrier widths, l ength of the intrinsic region and InGaAs composition were determined f rom high-resolution X-ray diffractometry. As the p-i-n diode has a wel l 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 measure d value is compared to previously reported values. 1998 Published by E lsevier Science B.V. All rights reserved.