Chemical and structural characterization of GaSb(100) surfaces treated by HCl-based solutions and annealed in vacuum

Abstract

The surface preparation of GaSb(100), based on HCl solutions, was studied by x-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM). The chemical and structural analysis by XPS and AFM indicates that the GaSb surface treated by HCl followed by a 2-propanol rinse leads to a 1 to 2 nm oxide layer on the surface. The resulting smooth surface is slightly antimony rich. Surfaces rinsed in deionized water, after HCl-based etching, possess a thicker overlayer, which is depleted of antimony. The surface morphology becomes rough rapidly upon reexposure to air after the HCl/H2O treatment. Other etching processes, including a tartaric acid based etchant, were investigated. Tartaric acid-based etches yield a highly nonstoichiometric surface along with an inhomogeneous etching morphology. The rates of desorption of surface oxides were determined by XPS analysis under ultrahigh vacuum conditions and the typical temperatures of desorption for the constituent chemical component comprising the surface layer were determined.

Improved characteristics for Au∕n-GaSb Schottky contacts through the use of a nonaqueous sulfide-based passivation

“…This native oxide consists of gallium and antimony oxides, as well as elemental antimony, all in the atomic ratio of 1:0.58:0.23. 4 The highly nonideal rectifying behavior of the as-received GaSb surface is attributed, in part, to the thick oxide layer between the metal and the GaSb surface. A surface dielectric layer, such as an oxide, can impact the current transport in several regards.…”

“…Preparation of the GaSb surface by dipping in concentrated HCl and rinsing with 2-propanol reduces the thickness of the oxide overlayer from 3 -5 to 1 -2 nm based on x-ray photoemission spectroscopy (XPS) measurements. 4 The Schottky diode fabricated on a GaSb surface after such HCl treatment exhibits both an increased zero-bias barrier height ͑0.46 eV͒ and a decreased ideality factor (1.89). This is associated with the reduction in thickness of the native oxide.…”

“…Air oxidation of GaSb at room temperature results in a thick overlayer of native oxide and a high concentration of elemental antimony at the oxideGaSb interface. [2][3][4] The presence of elemental Sb at the surface can lead to device degradation. Due to its metallic nature, Sb can increase the surface leakage current and lead to the generation of gap-region surface states, reducing the minority carrier lifetime and limiting device performance.…”

Modifications of the electronic structure of GaSb surface by chalcogen atoms: S, Se, and Te

“…Air oxidation of GaSb leads to a thick overlayer of native oxide on the surface, along with a high concentration of elemental antimony. [2][3][4] As for most other III-V semiconductors, the high density of energy states within the band-gap region results in a large surface band bending and reduces a minority carrier lifetime. It is important to control the electronic structure and state density of the GaSb surface to increased control, reliability, and performance of electronic devices.…”

Molecular beam epitaxy on gas cluster ion beam-prepared GaSb substrates: Towards improved surfaces and interfaces

“…In the past, surface preparation methods to replace CMP produced surface oxides with thinner, more stable, and thermally desorbable surface oxides have included wet chemistry [2][3][4][5], sulfide-based surface passivation [6,7], ultraviolet radiation [8], and dry ion etch techniques [9]. Although these methods have shown varying degrees of success, none can be considered as a final polish.…”