Thermal annealing behaviours of GaP(001) surface

Abstract

Thermal degradation of GaP(0 0 1) surfaces has been studied using spectroellipsometry (SE), optical microscopy, scanning electron microscopy (SEM), ex situ atomic force microscopy (AFM), x-ray photoelectron spectroscopy (XPS) and photoluminescence (PL) techniques. The SE data suggest that thermal annealing causes removal of the native oxide at temperatures T < 600 °C and surface roughening at T ≥ 600 °C. The XPS spectra confirm the native oxide removal from the GaP surface. The AFM images provide rms roughnesses of ∼0.6 nm at T < 600 °C and ∼2 nm (∼15 nm) at T = 600 °C (800 °C), suggesting a rapid increase in the rms roughness with an increase in T above 600 °C. The reduction in PL intensity is observed for T ≥ 500 °C. The Ga droplets, observed by optical microscopy and SEM, appear at T > 600 °C, i.e. after the native oxide is removed from the GaP surface. These facts allow us to draw the conclusion that the surface native oxide acts as a good passivation film against annealing-induced PL degradation and thermal decomposition.

Properties of GaAs(001) surfaces thermally annealed in vacuum

“…25,37 Thermal annealing of GaP͑001͒ in vacuum caused a thinning of the native GaP oxide ͑T Ͻ 600°C͒. 38 In the case of GaAs͑001͒ surface, we observed no clear thinning of the native GaAs oxide for T Յ 500°C but observed an evidence of the thermal degradation for T Ͼ 500°C ͓Fig. 4͑b͔͒.…”

Nanoscale Footprints of Self-Running Gallium Droplets on GaAs Surface

“…Upon removal from the growth chamber, a large milky area can be seen on the surface of the sample with unassisted naked eyes. This milky region is, in general, comprised of Ga droplets which are the result of a non-congruent evaporation of GaAs at high temperatures [20]. With high resolution SEM and AFM in tapping mode, Ga droplets and their trails are observed clearly indicating droplet motion.…”

GaP collector development for SiGe heterojunction bipolar transistor performance increase: A heterostructure growth study

“…Higher postannealing temperatures are not suitable, because uncovered GaP layers start to decompose. 35,36 After cooling down back to 50 C, a final h/2h XRD measurement was carried out. Figure 4(a) shows only the 50 C, 250 C, 550 C and the back to 50 C results of this experiment for the sake of clarity.…”