Consequence of Galvanic Displacement Reaction on Digital Photocorrosion of GaAs/Al0.35Ga0.65As Nanoheterostructures

Abstract

GaAs/AlGaAs semiconductor nanoheterostructures have found attractive application in the field of biosensing based on the effect of digital photocorrosion (DIP). The sensitivity of semiconductor–nanoheterostructure-based biosensors depends on the precision of controlling the process of DIP, which is highly sensitive to the surface presence of electrically charged biomolecules. To explore further this process, we have investigated the role of a galvanic displacement (GD) reaction on DIP of GaAs/Al0.35Ga0.65As (001) nanoheterostructures. Deposition of ionic gold on the GaAs surface induces spontaneous electron transfer between the semiconductor and ionic gold, which affects the photocorrosion of GaAs/AlGaAs layers observed simultaneously with the photoluminescence effect. The immediate consequence of the electron transfer from GaAs toward Au3+ is a significantly increased rate of DIP. At the same time, the formation of neutralized gold nanoparticles and Au–Ga alloy takes place on the surface of photocorroding nanoheterostructures. In the presence of 2.8% solution of ammonia and 0.1 mM gold chloride, a significantly reduced rate of deposition of gold nanoparticles is observed. This allows achieving layer-by-layer removal of the investigated material, which is sensitive to perturbations induced by surface immobilized electrically charged molecules. We have elaborated various factors stimulating photocorrosion of the GaAs/Al0.35Ga0.65As nanoheterostructures and we demonstrate the biosensing potential of an innovative GD-based DIP sensor.