Stability of biofunctionalized GaAs surface

Abstract

For a semiconductor based biosensor, functionalization of the surface and the stability of the semiconductor-biomolecule interface are the primary issues to be addressed by researchers. We have investigated a variety of strategies to passivate (001) GaAs surface with a long chain hexadecanethiol (C 16 H 33 SH: T16). GaAs substrates were cleaned and etched either with ArF excimer laser irradiation in an atmospheric environment or with conventional wet etchants. The effect of surface passivation and stability of the interface were evaluated using photoluminescence (PL) measurements. Significant cleaning of the (001) GaAs surface has been achieved with an ArF laser, as evidenced by the up to 4-fold increase of the PL signal. This compares to the 12-fold enhancement of the PL signal from samples that were alternately etched in solutions of NH 3 /H 2 O and HCl/ethanol. A combination of a diluted base and an acid possibly provides the cleanest surface and therefore the highest surface functionalization efficacy and long term stability upon thiolation.

Strong subbandgap photoconductivity in GaP implanted with Ti

“…In the case of other III to V semiconductors, such as GaAs, laser processing in air can produce a time‐stable surface passivation . A GaAs surface cleaning by removing a low‐quality native oxide, followed by S passivation, by means of excimer laser irradiation has been also reported, showing in some cases an increase of the photoluminescence intensity …”