Structural, electric, and optical properties of MgGa2Se4 epilayers grown by hot wall epitaxy method

The epilayer growth of the MgGa2Se4 compounds was successfully achieved through the hot wall epitaxy method. The grown layer was accumulated along the <116> direction onto the GaAs(100) substrate. From the Hall effect measurement, the mobility was determined to be 264 cm2/Vs at 293 K. At a high temperature range (T>150 K), it tended to decrease as a function of T−3/2 by increasing the temperature, and increase as a function of T3/2 at the low-temperature range (T<100 K). In the photocurrent (PC) measurement, we observed the A, B, and C peaks corresponding to 529.9 (2.3398 eV), 495.2 (2.5037 eV), and 477.6 nm (2.5960 eV) at 10 K, respectively. Three peaks of A, B, and C were caused by the band-to-band transitions from the valence band state of Γ4(z), Γ5(x), and Γ5(y) to the conduction band state of Γ1(s), respectively. By comparing the results of PC and absorption, the temperature dependence of the optical bandgap energy was well interpreted using Varshni's relation Eg(T)=2.3412−8.87×10−4 T2/(T+251).

► The epilayers of MgGa2Se4 were first grown through the hot-wall-epitaxy method.
► From the photocurrent measurement, the bandgap energy of MgGa2Se4 was found.
► A splitting of the valence band into three subbands was extracted through the photocurrent measurement.
► Structural, electric, and optical properties were performed.