Electrochemical passivation of gallium arsenide surface with organic self-assembled monolayers in aqueous electrolytes

Abstract

Self-assembled monolayers of octadecylthiol (ODT) were reconstituted on freshly etched gallium arsenide (n-GaAs) for the electrochemical stabilization against decomposition of the surfaces (passivation) in aqueous buffers. The surface composition was evaluated by x-ray photoelectron spectroscopy to optimize the surface treatment before ODT deposition. Electrochemical properties of the monolayers were monitored by cyclic voltammetry and impedance spectroscopy. The impedance spectrum of the photoetched n-GaAs after the deposition of the ODT monolayer was stable in an aqueous electrolyte at pH=7.5 for more than 24 h within the sensitivity of our experimental technique. The effective passivation of GaAs surfaces is an essential step towards biosensor applications.

Influence of Thiol Coupling on Photoluminescence of Near Surface InAs Quantum Dots

“…However, effects of the surface modification on the luminescence properties have been discussed in terms of increased PL intensity and PL decay time only for bulk GaAs [15,16]. In previous studies, we demonstrated the electrochemical stabilization of the GaAs surface by the ODT monolayer deposition in aqueous electrolytes [2]. The ODT monolayers turned out to be stable even after more than one month in air [8].…”

“…This may be used to investigate changes in the density of surface states. Recently, the electrochemical passivation of GaAs surfaces in aqueous electrolytes with self-assembled monolayers (SAMs) of octadecylthiol (ODT) has been reported [2]. Here we discuss effects of ODT monolayer deposition on the QD PL in air.…”

“…The ODT monolayers were deposited self-assembling from the solution as reported previously [2]. Prior to the SAMs deposition, the cleaned InAs QD samples were dipped into concentrated HCl for 1 min.…”

Corrosion Protection and Long-Term Chemical Functionalization of Gallium Arsenide in an Aqueous Environment

“…[21] It was recently suggested that ODT surfaces, assembled with a photochemical etching method, keep impedance spectra stable for several hours in an aqueous electrolyte solution under conditions of zero-current potential. [22] Further, as a promising alternative to the surface passivation of gallium arsenide with organic monolayers, benzoic and dicarboxylic acid derivatives have been introduced. [23±25] Their chemisorption to GaAs has been shown to control the work function of the semiconductor, [23] and the compatibility of the resulting interface with at least some biological environments has recently led to the development of the first GaAs-based biosensor for the direct detection of micromolar levels of nitric oxide under physiological conditions.…”

Electrochemical stabilization of crystalline silicon with aromatic self‐assembled monolayers in aqueous electrolytes

“…Previously, we demonstrated the electrochemical passivation of GaAs surfaces with monolayers of alkylthiols under physiological conditions, i.e., at neutral pH in aqueous electrolytes [3,4]. Suppression of the surface state density due to the covalent As-S coupling could also be observed by photoluminescence signals from near-surface InAs quantum dots [5].…”