Determination of Optical Properties of MOVPE-Grown InxGa1-xAs/InP Epitaxial Structures by Spectroscopic Ellipsometry

Abstract

InxGa1−xAs epitaxial layers with different AsH3 flows have been grown on InP substrate with the MOVPE system. It has been found that AsH3 flow variation affects the In concentration of InGaAs/InP structure because the increment of AsH3 flow increases the In concentration due to the weak bond between In and As. The variation of AsH3 flow during the growth process has affected crystal quality and optical properties of InGaAs epilayer. The optical properties of the structure have been determined by spectroscopic ellipsometry and spectrophotometer. The variation of In concentration has changed the refractive index value of the structure. The thickness of the samples and refractive index values have been obtained by spectroscopic ellipsometry. The obtained findings show that the reflection has been improved with high AsH3 flow resulting from surface quality improvement. In addition, it has been observed that the energy band gap has been decreased as a function of the increment of AsH3 flow because the structure band gap approaches the InAs structure at the high In concentration.