High resistivity LT-In0.47Ga0.53P grown by gas source molecular beam epitaxy

Low-temperature (LT) growth of In_0.47Ga_0.53P was carried out in the temperature range from 200 to 260°C by gas source molecular beam epitaxy using solid Ga and In and precracked PH₃. The Hall measurements of the as-grown film showed a resistivity of ∼10⁶ Ω-cm at room temperature whereas the annealed film (at 600°C for 1 h) had at least three orders of magnitude higher resistivity. The Hall measurements, also, indicated activation energies of ∼0.5 and 0.8 eV for the asgrown and annealed samples, respectively. Double-crystal x-ray diffraction showed that the LT-InGaP films had ∼47% In composition. The angular separation, Δθ, between the GaAs substrate and the as-grown LT-InGaP film on (004) reflection was increased by 20 arc-s after annealing. In order to better understand the annealing effect, a LT-InGaP film was grown on an InGaP film grown at 480°C. While annealing did not have any effect on the HT-InGaP peak position, the LT-InGaP peak was shifted toward the HT-InGaP peak, indicating a decrease in the LT-InGaP lattice parameter. Cross-sectional transmission electron microscopy indicates the presence of phase separation in LT-InGaP films, manifested in the form of a “precipitate-like” microstructure. The analytical scanning transmission electron microscopy analysis of the LT-InGaP film revealed a group-V nonstoichiometric deviation of ∼0.5 at.% P. To our knowledge, this is the first report about the growth and characterization of LT-InGaP films.