Sulphur passivation of GaSb, InGaAsSb and AlGaAsSb surfaces

摘要

The effects of electrochemical treatment in either 21%(NH_4)_2S-H_2O or 16%Na_2S-C_3H_7OH solutions on the surface properties of GaSb, In_(0.23)Ga_(77)As_(0.18)Sb_(0.82) and Al_(0.34)Ga_(0.66)As_(0.025)Sb_(0.975) have been investigated by complementary use of Variable Angle Spectroscopic Ellipsometry (VASE) and X-ray Photoelectron Spectroscopy (XPS). We have shown that electrochemical sulphuration enables to produce 94-350 nm thick insulating overcoats with good surface morphology. The main components of the passivating layers are Ga_2S_3 and Sb_2S_5when formed on GaSb, while additional components of In_2S_3, admixture of Al_2O_3 and appearance of Al-As bond were observed on InGaAsSb and AlGaAsSb, respectively. The main feature distinguishing the effect of electrochemical treatment in Na_2S-C_3H_7OH when comparing to those in (NH_4)_2S-H_2O is that passivating layers contain additional components of Na_2SO_3 and/or Na_2SO_4.