Control of chemical composition and band gap energy in Ga In1 − − Al As on InP during molecular beam epitaxy

Abstract

The growth of Ga x In 1-x-y Al y As, lattice matched with respect to InP, by molecular beam epitaxy (MBE) is investigated. To achieve a precise prediction over the chemical composition, the quaternary layers were produced by the simultaneous growth of the ternaries Ga 0.47 In 0.53 As and Al 0.48 In 0.53 As. The aluminium content y of the quaternary layer is independently preset by the ternary growth rates. The quaternary samples were characterized by X-ray diffraction as well as by low-temperature (4.2 K) and room-temperature (RT) photoluminescence (PL). At both temperatures, we found a linear dependence of the energy at maximum PL intensity on the aluminium content y in the quaternary layer. The calculated linear fit for the quaternary data points corresponds closely with the linear interpolation between our Ga 0.47 In 0.53 As and Al 0.48 In 0.52 As data. These results enabled the determination of the equation system, giving the composition x, y of Ga x In 1-x-y Al y As as a function of the measured lattice mismatch Δd/d and PL.