Effect of different P/As ratio on the optical and structural properties of GaAs_1−xP_x/GaAs

Abstract

The GaAs 1−x P x /GaAs ternary alloys were grown on n-GaAs (100) substrate with different P/As flux ratio by solid source molecular beam epitaxy (MBE) system using GaP decomposition source. In order to obtain smooth interface and lattice mismatch structures we have used both continuous growth (CG) and graded growth (GG) methods. The range of lattice parameters in the graded epilayer and phosphorous composition in the samples were determined by the high-resolution X-ray diffraction (HRXRD) rocking curve simulation. The critical energy points of the interband transition edges of the structures were determined by line-shape analyses on their dielectric functions (DF) using spectroscopic ellipsometry (SE) measurements at a room temperature in the 0.5-5 eV photon energy region. Also, surface and interface phenomenon of the structures were discussed by using ellipsometric data. Phosphorous compositions of the ternary alloys were also calculated by photoluminescence (PL) emission peak positions at room temperature and using the bowing parameter obtained by fitting to critical points.

New method and treatment technique applied to interband transition in GaAs1−x Px ternary alloys

“…The angle of incidence of the light beam was fixed at 70°on the surface of the samples. The SE measurements for the samples were made at room temperature under atmospheric conditions [1]. Before the measurements, the surface of the samples was cleaned using methanol to remove any contamination artifacts.…”

“…The exponent has the values of − 1 2 0 1 2 , and −1 for the one-dimensional, two-dimensional, three-dimensional, and excitonic critical points, respectively [1][2][3][4][5]. It is noted that C A Φ E and Γ are the fitting parameters.…”

“…The composition dependence of the higher energy gaps (named critical energy points) and spin-orbit splitting energy can be obtained by evaluation of the dielectric function (DF). The DFs and optical properties of the semiconductor structures can be obtained precisely by evaluation of spectroscopic ellipsometry (SE) measurements [1][2][3][4][5]. To determine the CP energies from DF for a layer or layered semiconductor structures several models were developed through Harmonic Oscillator Approximation (HOA) and Effective-Medium Approximation (EMA), which are reviewed in Ref.…”

“…Alloy compositions of the alloys were determined using high resolution X-ray diffraction [1]. Also, a bowing parameter of the band gap energy was obtained from SE study due to disordered phosphorous content.…”

“…Also, a bowing parameter of the band gap energy was obtained from SE study due to disordered phosphorous content. In this paper we presented a new method that can be used for calculations of the critical points energies and the bowing parameter of band gap energy due to disordered phosphorous content of GaAs 1− P /GaAs (100) ternary alloys, which are grown by using MBE [1]. This new method enables transformation of a wide class of functions, initially containing a set of nonlinear fitting parameters, into a set of slope lines [8].…”