Growth and electrical/optical characteristics of unintentional p-type BaIn2Se4 epilayers grown using hot wall epitaxy method

The epitaxial growth of photoconductive BaIn2Se4, which has orthorhombic structures, was first achieved through the hot wall epitaxy method. The electrical and optical characteristics of these epilayers were discussed. From the Hall effect measurement, in a high-temperature range of T>150 K, the mobility decreased as a function of T−1 and its scattering was mainly due to the acoustic phonon mode of lattice vibrations through a deformation potential. In contrast, the mobility decreased in proportional to T0.6 in a low-temperature range of T<150 K and its decrease was caused by the impurity ion scattering. Also, from the relation between the reciprocal temperature and the carrier concentration, two dominant levels 136.9 and 27.9 meV were extracted out and they were estimated to be the activation energies of the shallow acceptor levels caused by the native defects of the upper edge of the valence band. In addition, from the optical absorption measurement, the bandgap variation of BaIn2Se4 epilayers extracted was well expressed by Eg(T)=2.626 eV-4.99×10−3T2/(T+559).