The surface chemical properties of gallium antimonide(Ga Sb) after ammonium sulfide((NH4/2S) solution passivation have been studied by X-ray photoelectron spectroscopy(XPS), time of flight secondary ion mass spectroscopy(TOF-SIMS) and I–V measurement. An advantage of neutral(NH4/2SCS solution over pure(NH4/2S solution and alkaline(NH4/2SCS solution has been found in the ability to passivate the Ga Sb surface by contrast and comparison. It has been found that alkaline(NH4/2SCS solution passivation effectively removes oxides of the Ga Sb surface and forms sulfide products to improve device performance. TOF-SIMS complementally demonstrates that pure(NH4/2S passivation did form sulfide products, which are too soluble to really exist. The lowest roughness determined using a 3D optical profilometer and the highest improved SBD quality proved that neutral(NH4/2SCS solution passivation worked much better in improving the surface properties of Ga Sb. The surface chemical properties of gallium antimonide (Ga Sb) after ammonium sulfide ((NH4 / 2S) solution passivation have been studied by X-ray photoelectron spectroscopy (XPS), time of flight secondary ion mass spectroscopy (TOF- SIMS) and I- An advantage of neutral (NH4 / 2 SCS solution over pure (NH4 / 2 SCS solution has been found in the ability to passivate the Ga Sb surface by contrast and comparison. It has been found that alkaline ( NH4 / 2 SCS solution passivation effectively remove oxides of the Ga Sb surface and forms sulfide products to improve device performance. TOF-SIMS complementally demonstrates that pure (NH4 / 2S passivation did form sulfide products, which are too soluble to really exist. The bottom roughness. determined using a 3D optical profilometer and the highest improved SBD quality proved that neutral (NH4 / 2SCS solution passivation worked much better in improving the surface properties of Ga Sb.