Behaviors of GaSb and InSb III-V Semiconductor Surfaces in the Wet Chemical Solutions

Abstract

III–V compound semiconductors can be used as new channel materials because of their high carrier mobilities and low power consumption. Among various III–V compound semiconductor materials, Sb-based III-V semiconductors such as gallium antimonide (GaSb) and indium antimonide (InSb) are also gaining attention as a channel material, because they have extremely high carrier mobilities and an excellent lattice matches with various III–V ternary and quaternary compounds. However, Sb-based III-V semiconductors are easily oxidized by atmospheric oxygen and forms native oxide layers. Therefore, effective surface preparation with an understanding of its surface chemistry is required. However, the reaction kinetics in the cleaning / surface preparation process and the mechanisms of etching and oxidation in the overall process have not yet been elucidated. In the current study, the effect of representative wet treatments in acidic and basic solutions on the GaSb and InSb surface behavior is studied. When GaSb and InSb were treated in acidic hydrochloric acid - hydrogen peroxide mixture (HPM) solutions, the etching rates and oxide layer thicknesses of both GaSb and InSb surfaces decreased, and the contact angles increased as the H2O2 concentration was decreased by dilution. In addition, the results of the XPS measurements confirmed that the XPS Ga3d and In3d5 /2 peak area ratios of Ga2O3/GaSb and In2O3/InSb decreased with decreasing H2O2 concentration in HPM. Based on the observed results, it is suggested that H2O2 serves as a strong oxidant in acidic HPM solutions and the overall surface reaction of GaSb and InSb in HPM solution depends on the surface oxidation by H2O2. In addition, the Sb 3d3/2 peak area ratios of Sb2O3/GaSb (or Sb2O3/InSb) were not significantly changed with H2O2 concentration in HPM. Therefore, it is thought that the surface oxidation behavior of Sb-based materials is determined by the group III elements, Ga and In, rather than the group V element, Sb. On the other hand, in basic ammonium hydroxide - hydrogen peroxide mixture (APM) solutions, H2O2 tends to decompose into OH-, etching species, so that Ga atoms on the GaSb surface or in the Ga oxide can be etched by OH- to form aqueous H2GaO3 - ions. Therefore, H2O2 cannot contribute to the oxidation of GaSb in basic APM solutions, but the surface oxidation of GaSb is accelerated as the solution is diluted by H2O. In APM solution, H2O works as an oxidant on the GaSb and InSb surfaces.