In situ flashes of gallium technique for oxide-free epiready GaSb (100) surface

The authors report a novel in situ technique for desorption of native oxides from GaSb (100) substrates. In the proposed approach, flashes of atomic gallium (FLAG) are irradiated onto a heated substrate to convert the nonvolatile Ga2O3 to volatile Ga2O. The conventional thermal oxide desorption (TOD) technique was compared with the proposed FLAG technique. Reflection high energy electron diffraction was used to monitor the oxide desorption. Oxide desorption by the FLAG technique was observed at 470 °C, which is ∼80 °C lower than the TOD technique (550 °C). Atomic force microscopy of the GaSb buffer grown using the FLAG technique reveals an atomically smooth surface. Unipolar barrier midwave infrared detectors based on InAs/GaSb type II superlattices were grown using the two approaches. The dark current from a representative FLAG device measured at T = 77 K and Vb = −0.1 V was 5.28 × 10−6 A/cm2 compared with a reference TOD device which had a dark current of 8.96 × 10−4 A/cm2 measured under identical condi...