Chemical Cleaning of GaSb (1,0,0) Surfaces

Abstract

normalGaSb (1,0,0) surfaces have been cleaned by chemical passivation and later heat‐treatment in ultrahigh vacuum conditions. Four different etching solutions consisting of an oxidant and an acid for oxide dissolution have been studied. With the H2SO4:H2O2:H2O the surfaces become very rough, unevenly covered with oxides, and not suitable for later epitaxial growth. The remaining three etchants studied, normalHCl:H2O2:normalNaKfalse(normaltartratefalse) , HF:HNO3:CH3COOH , and Br:methanol, leave rather smooth surfaces covered with a thin passivating layer, probably consisting of pure Sb, Sb2O3 , and Ga2O3 , which can be easily removed by heating the samples in ultrahigh vacuum at temperatures between 480° and 510°C.

GaSb oxide thermal stability studied by dynamic-XPS

“…This regime exists in the temperature range of 550-740 K. The desorption of Sb is not unexpected in this temperature range since Sb capping layers are reported to desorb at 573 K in UHV. 10,23 In this work, the Ga 2 O 3 is not found to desorb until the temperature range of 840-860 K, which is significantly higher than the previously reported range of 753-783 K. 11,18,24 Other than potential errors in temperature measurements between the various studies, at least two possible explanations exist to account for these discrepancies. It is possibly due to differences in the annealing environment since the previous work utilized anneals in flowing 18 H 2 or flux 24 of Sb.…”

“…10,23 In this work, the Ga 2 O 3 is not found to desorb until the temperature range of 840-860 K, which is significantly higher than the previously reported range of 753-783 K. 11,18,24 Other than potential errors in temperature measurements between the various studies, at least two possible explanations exist to account for these discrepancies. It is possibly due to differences in the annealing environment since the previous work utilized anneals in flowing 18 H 2 or flux 24 of Sb. Another potential explanation is that in the previous studies 11,18,24 the samples were brought to, and held at, a fixed temperature for a specific time interval before cooling to room temperature for analysis, rather than being dynamically ramped as has been done in this study.…”

“…It is possibly due to differences in the annealing environment since the previous work utilized anneals in flowing 18 H 2 or flux 24 of Sb. Another potential explanation is that in the previous studies 11,18,24 the samples were brought to, and held at, a fixed temperature for a specific time interval before cooling to room temperature for analysis, rather than being dynamically ramped as has been done in this study. It is also interesting to note that there is a gradual increase in the Ga 2 O 3 intensity between 700 K and 840 K. Since this coincides with the small reduction in the O 1s area, it is presumed that this increase in intensity is due to the removal of C-O species that originate in adventitious carbon on the starting surfaces.…”

Intense terahertz emission from molecular beam epitaxy-grown GaAs/GaSb(001)

“…The (001) n-GaSb substrates were subjected to chemical preparation steps to achieve a clean epi-ready surface, consistent with previous studies. 11,12 The substrates were immersed in HCl for 1 min to etch off the residual oxides along with pre-and postdegreasing steps. To form a protective oxide layer, the substrates were submerged in 0.2% Br-methanol solution for 30 s. The substrates were outgassed in the loading chamber for 1 h at a nominal temperature of 350 C. The oxide layer was thermally desorbed in the growth chamber under an As 4 flux of 5 Â 10 À6 Torr.…”

Surface State Passivation and Optical Properties Investigation of GaSb via Nitrogen Plasma Treatment

“…These have included incorporating interfacial or capping layers composed of wide band gap materials, wet chemistry modification approaches, in situ hydrogen plasma treatment, and the deposition of high- k dielectrics. 19,21−23 Sulfur (S) passivation has long been recognized as a useful method for removing surface states. 24,25 By adjusting the treatment conditions, the oxide layer and surface dangling bonds can be effectively etched or filled.…”