Sustainable digital photocorrosion of GaAs/Al0.35Ga0.65As nanoheterostructures

Digital photocorrosion (DIP) of a semiconductor is a two-cycle process involving an irradiation and a dark phase. DIP of GaAs/AlGaAs has been investigated for detecting electrically charged biomolecules, such as bacteria and spores immobilized on the surface of such microstructures. Attractive biosensing results have been reported with DIP of a single GaAs-AlGaAs pair of nanolayers However, experiments concerning application of two, or a greater number of GaAs-AlGaAs nanolayers for repeated biosensing were less successful due to continuous accumulation of Ga- and Al-byproducts on the surface of biochips processing in phosphate buffered saline (PBS). To alleviate the problem of inefficient removal of GaAs/AlGaAs photocorrosion products in PBS, we examined a hybrid process consisting of replacing PBS with NH4OH-based etchant during dark phase of the DIP process. A computer-controlled protocol allowed sustainable DIP of a stack of GaAs-AlGaAs nanolayers observed in situ with non-vanishing photoluminescence intensity from GaAs. The proposed method has a great potential for the technology of regenerable biosensors designed for quasi-continuous environmental monitoring.