Jassim Shahbaz, M.Sc.
Research Staff Member
“GaN/InGaN heterostructure sensors for detection of gases present in human breath such as hydrogen sulphide”
Bio and chemical sensors based on InGaN heterostructures are increasingly becoming an interesting subject for scientific researchers. The chemical stability, inertness and sensitivity to its environment make GaN a suitable material for such sensing applications. This sensitivity is attributed to the adsorption of molecules on the surface of such structures which modifies the bandgap. This modification can be read out optically by the photoluminescence signal providing an added advantage of avoiding electrical contacts. The sensor structure along with surface functionalization needs to be optimized for the best sensitivity and selectivity for specific gas or biomolecules before commercial utilisation of such sensors. After final development, such sensor data is intended to be used by medical professionals to analyse the health state of a patient.
The research work done in this PhD project is under the umbrella of the Graduate School PULMOSENS (GRK 2203) “Semiconductor-based nano structures for the highly sensitive optical analysis of gases and bio-materials”.
Open Positions for Bachelor or Master Thesis:
“GaN sensor structure functionalized for gas sensing by metal cover layer”
The goal of this study is to use metal layers on the sensor surface to influence/improve the detection of hydride gases, initial results have been published in our recent paper (D. Heinz et al., J. Sel. Topics QE 2017). Preliminary studies would be concerned with deposition of thin metal films of Au and Pd on the GaN sensor surface and to study the interaction with hydrogen gas. The thickness of such a layer would be an interesting parameter which could hugely influence the sensitivity of the sensor. Other parameters of interest would be sensitivity based on the different metal layers, recovery behaviour (time) and the influence of temperature.
Based on the initial results other hydride gases such as ammonia and hydrogen sulphide may be used later for a more broad study. The goal would be to make the sensor highly sensitive and selective to particular gas molecules. Characterization techniques such as photoluminescence measurements (PL), scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS) will be applied for a comprehensive analysis.
Conference Talks/Poster Presentations
1- J. Shahbaz, M.F. Schneidereit, B. Hörbrand, S. Bauer, K. Thonke, and F. Scholz, “Optimising InGaN heterostructures for bio and gas sensors”, poster at 17th European Workshop on Metalorganic Vapour Phase Epitaxy EWMOVPE XVII, Grenoble, France, June 2017.
2- J. Shahbaz, M.F. Schneidereit, D. Heinz, B. Hörbrand, F. Huber, S. Bauer, K. Thonke, and F. Scholz, “Simulation and verification of InGaN heterostructure-based gas and bio sensor design”, poster at 12th Int. Conf. on Nitride Semiconductors, ICNS 2017, Strassbourg, France, July 2017.
3- J. Shahbaz, “InGaN heterostructures for gas sensing”, PulmoSens Fall Meeting, Reisensburg, Günzburg, Germany, Oct. 2017.
4- J. Shahbaz, Y. Liao, M.F. Schneidereit, and F. Scholz, “InGaN heterostructures as gas sensors”, 32nd DGKK Workshop Epitaxy of III/V Semiconductors, Freiburg, Germany, Dec. 2017.