Speaker
Description
Quantum Semiconductors and Photon-based BioNanotechnology Group, Laboratoire Nanotechnologies et Nanosystèmes (LN2) - CNRS IRL-3463, Interdisciplinary Institute for Technological Innovation (3IT), Department of Electrical and Computer Engineering, Université de Sherbrooke, 3000, boul. de l’Université, Sherbrooke, Québec J1K 0A5, Canada
Digital photocorrosion (DIP) of a semiconductor is a two-step cyclic process consisting of an irradiation phase followed by a dark phase.[1] DIP applied to GaAs/Al$_{0.35}$Ga$_{0.65}$As heterostructures has been investigated for the detection of electrically charged biomolecules, such as bacteria and spores immobilized on the surface of such devices. Promising biosensing performances have been reported, particularly for DIP on a single pair of GaAs/AlGaAs nanolayers.[2]
Although DIP processed GaAs/AlGaAs surfaces offer favorable conditions for the formation of high quality alkanethiol self-assembled monolayers [3], extending DIP to multiple pairs of GaAs/AlGaAs nanolayers for repeated biosensing has proven challenging. Progressive accumulation of Ga- and Al-byproducts on the surface of biochips processed in phosphate buffered saline, and the relatively complicated structure of photoluminescence (PL) intensity maxima (PL$_{\text{MAX}}$) revealed during photocorrosion of GaAs/AlGaAs nanolayers were identified as the potential key factors limiting the successful implementation of this technology for quasi-continuous biosensing.
To shed the light on the dependence of PL intensity emission on the absorption depth of PL exciting photons, we carried out numerical simulation of the DIP process for GaAs nanolayers separated by different thickness of AlGaAs nanolayers. The modeling indicated that complex shape of PL$_{\text{MAX}}$ for a structure consisting of a GaAs (6 nm)/AlGaAs (10 nm) multilayer stack originates from a weak PL emission by deeply located GaAs nanolayers in the microstructure. This has been verified by the DIP experiments involving GaAs/AlGaAs nanoheterostructures with the thickness of AlGaAs layer increased to 20 nm. The results suggest a possibility of designing nanoheterostructures with stacks of GaAs/AlGaAs nanolayers exhibiting PL emission exclusively from individual GaAs nanolayer during the DIP process. In addition to the increased thickness of the PL screening AlGaAs nanolayer, this effect can be tuned by selective doping of the investigated nanoheterostructures. Nanoscale resolution of the DIP process of GaAs/AlGaAs nanoheterostructures is of the potential interest for the fabrication of advanced devices at attractive cost.
[1] M.R. Aziziyan et al., ACS Applied Materials & Interfaces, 11 (2019) 17968-17978.
[2] E. Nazemi et al., Biosensors and Bioelectronics, 93 (2017) 234-240.
[3] R. St-Onge et al., Applied Physics Letters, 118 (2021) 222102.
| Keyword-1 | Photoluminescence |
|---|---|
| Keyword-2 | Photo-atomic layer etching |
| Keyword-3 | GaAs/AlGaAs quantum well |