In an attempt to rationalize empirically developed GaSb device optimization using alcoholic versus aqueous sulfide solutions, synchrotron radiation photoemission spectroscopy (SXPS) has been applied to study the chemical composition and the electronic properties of the GaSb(100) surface treated with ammonium sulfide dissolved in water versus 2-propanol. In addition the initial native oxide layer on GaSb(100) surface has been analyzed in detail. The variation of the solvent leads to variations in the chemical composition and electronic structure of the final sulfide layers. In the deeper parts of the passivation layers, the Ga/Sb atomic ratio is around 1 for 2-propanol and 2 for aqueous solution. Right at the surface it is 0.15 and 0.4, respectively. Valence band maximum and core levels of the sulfide layers are found at 0.26 and 0.4 eV higher binding energies using 2-propanol versus aqueous solution. Almost no oxygen is left on the surface treated using ammonium sulfide in 2-propanol, while with use of aqueous ammonium sulfide solution, inclusions of Ga 2 O 3 are found. The carbon contamination is reduced 4 times using alcoholic, while it is increased by a factor of 1.25 with aqueous solution.

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