Band offsets determination and interfacial chemical properties of the Al2O3/GaSb system

Abstract

Band offsets of the Al2O3/GaSb system and various surface passivation treatments of the GaSb substrate by HCl, NH4OH, and (NH4)2S solutions were investigated by x-ray photoelectron spectroscopy. The extracted conduction and valence band offsets values of Al2O3 relative to GaSb are 2.4±0.1 eV and 3.4±0.2 eV, respectively. The presence of Ga–O and Sb–O bonds was detected after NH4OH surface treatment. In contrast, (NH4)2S and HCl solutions inhibit the Sb oxide formation. The lowest amount of Ga–O bands was obtained for (NH4)2S passivation. These results correlate with capacitance-voltage (C-V) measurements of Pd–Au/Al2O3/GaSb stacks which yielded the best characteristics for the S-based passivation.

Electron band alignment at the interface of (100)GaSb with molecular-beam deposited Al2O3

“…20,21 As the charging-induced energy shift depends on the insulator thickness, 20 the results obtained in Ref. 19 for a 3 nm ALD Al 2 O 3 layer may be reconciled with our conclusions by correcting them for a Ϸ0.3 V CV curve shift observed after exposure of a similar 3 nm thick ALD Al 2 O 3 film to ionizing radiation ͑see Fig. 9 in Ref.…”

“…18 Also, the derived VB offset of 3 eV is 0.4 eV smaller than that reported recently for the ALD Al 2 O 3 / GaSb interface on the basis of XPS measurements. 19 The latter discrepancy may be caused by positive charging of the oxide layer during XPS measurements due to heavy x-ray irradiation, 9 which would result in a downshift of the electron energy levels in Al 2 O 3 with respect to the levels in semiconductor substrate leading to a systematically larger VB offset. 20,21 As the charging-induced energy shift depends on the insulator thickness, 20 the results obtained in Ref.…”

Surface Passivation and Interface Properties of Bulk GaAs and Epitaxial-GaAs/Ge Using Atomic Layer Deposited TiAlO Alloy Dielectric

“…The O 2s spectra of these samples are close to the previous reported results. 29 From the Ga 3d spectrum it is evident that the Ga−O feature has multiple oxidation states for different samples including Ga 1+ and Ga 2+ probably due to Ga 2 O and GaO formation. It is important to note that the TiAlO deposition has resulted in a Ga−O peak that is centered at a lower binding energy for bulk GaAs samples.…”

Electrical and physical characterization of the Al2O3/p-GaSb interface for 1%, 5%, 10%, and 22% (NH4)2S surface treatments

“…5,7,14 However, ammonium sulfide ((NH 4 ) 2 S), a wet treatment shown to engineer a high-quality high-k/InGaAs interface, 15,16 has received little attention on GaSb. One study 12 reported the elimination of Sb oxides following 2% sulfide treatment. The x-ray photoemission spectroscopy (XPS) analysis further revealed the Ga oxide content to be lower for (NH 4 ) 2 S compared to NH 4 OH or HCl treatments.…”

“…5,6 The resulting defectdominated interface impairs Fermi Level movement, thereby limiting the channel charge modulation capability of metal-oxide-semiconductor field-effect-transistors (MOSFETs). 7 Together with atomic layer deposition (ALD), both wet 3,5,[8][9][10][11][12][13][14] and dry 7 chemical treatments have been explored on GaSb to overcome these detriments. Of these, HCl and hydrogen plasma treatments have been most effective in alleviating surface oxides, thereby improving the electrical properties of the high-k/GaSb interface.…”