Effect of intrinsic defects on the electron mobility of gallium arsenide grown by molecular beam epitaxy and metal organic chemical vapor deposition

Abstract

Temperature dependent electron mobility measurements are reported for lightly doped n-type gallium arsenide (GaAs) grown by metal organic chemical vapor deposition (MOCVD GaAs). Using the Brooks–Herring model, the charge state of the impurity scattering centers is deduced to be 1. The same measurements are reported for irradiated MOCVD GaAs, and it is deduced that the charge state of the defects introduced is also 1. These observations are different from previously reported mobility measurements on irradiated gallium arsenide grown by molecular beam epitaxy (MBE GaAs), in which it was deduced that multiply charged scattering centers are introduced by the irradiation. Photoluminescence and deep level transient spectroscopy are used to identify the defects present in the as-grown and in irradiated GaAs. Through the observation of the antisites, it is concluded that the MOCVD GaAs was grown under arsenic rich conditions and the MBE GaAs under gallium rich conditions. Moreover, the gallium vacancy defect (VGa) is observed in irradiated MOCVD GaAs, but not in irradiated MBE samples. The mobility measurements on the MOCVD samples imply that the VGa charge state defect is −1. It is speculated that the arsenic vacancy defect is introduced in irradiated MBE GaAs and its charge state is −2.