Optical characterization of a GaAs/In_0.5(AlxGa_1-x)_0.5P/GaAs heterostructure cavity by piezoreflectance spectroscopy

Optical properties of a lattice matched GaAs/In(0.5)(AlxGa(1-x))(0.5)P/GaAs heterostructure cavity have been characterized using piezoreflectance (PzR) measurements in the temperature range between 20 and 300 K. The measurements were carried out in the energy range of 1.3-6 eV. The PzR spectra of In(0.5)(AlxGa(1-x))(0.5)P at 20 and 300K clearly show a lot of interband transition features present at energies above the band edge. There is also a feature of interference-fringes oscillations observed in each PzR spectrum below band gap E0 of In(0.5)(AlxGa(1-x))(0.5)P. The oscillation period in between the PzR interference fringes can be utilized to determine the index of refraction (n) for the In(0.5)(AlxGa(1-x))(0.5)P at different temperatures. The Al composition x of In(0.5)(AlxGa(1-x))(0.5)P can be estimated from the evaluation value of E(0) by PzR. The obtained Al composition of x=0.691 is in good agreements with the original design for growing the quaternary compound. Electronic band structure of In(0.5)(AlxGa(1-x))(0.5)P is determined by the interband transitions from PzR. The temperature variations of the transition energies and index of refraction n for the In(0.5)(AlxGa(1-x))(0.5)P are analyzed discussed. The PzR is proven to be very sensitive in determining the optical parameters in III-V GaAs/InAlGaP/GaAs Fabry-Perot system.