Graphene based electronic and optoelectronic sensors, stability, reliability and wafer scale integration
Uzlu, Burkay; Lemme, Max C. (Thesis advisor); Neumaier, Daniel (Thesis advisor)
Aachen : RWTH Aachen University (2022)
Dissertation / PhD Thesis
Dissertation, Rheinisch-Westfälische Technische Hochschule Aachen, 2022
Graphene, the two dimensional crystal of carbon, provides outstanding electronic, optical and mechanical properties for a wide range of applications for future electronics and opto-electronics. It presents ultimately high carrier mobility due to the zero band gap nature between the conduction and valance bands. This semi-metallic material has been widely studied in the past decade after its first experimental discovery in 2004. Due to the high carrier mobility, graphene has been demonstrated as an ideal material for Hall sensors and radio frequency electronics. Additionally, surface enhancement of graphene via functional materials has been demonstrated as an efficient method for achieving various sensory devices such as colloidal quantum dot (CQD) enhanced graphene based photo-detectors. Graphene based sensors with such methods outperforming the conventionally used semiconductors by means of sensitivity and operation speed have been demonstrated. However, power requirements to operate these sensors together with the long term stability and the wafer scale integration to the conventional fabrication line have not been addressed adequately. In this presented work, graphene based electronic and optoelectronic devices such as Hall sensors and metal-insulator-graphene diode based photo-detectors with scalable fabrication approach are demonstrated along with the extensive stability and wafer scale fabrication analysis. Presented graphene based Hall sensors on flexible substrate are not only outperforming the existing state-of-the-art conventional semiconductor based Hall sensors, but also highly competitive with all other existing high performance graphene based technologies manufactured with non-scalable approach. In addition, CQD enhanced graphene based photo-detectors with a novel device structure, working in the visible and near infrared wavelengths, are demonstrated. The demonstrated photo-detectors show orders of magnitude lower power consumption than other demonstrated graphene based technologies and yet outperforming the conventional semiconductor based photo-detectors. Furthermore, a comprehensive analysis of the status for the wafer scale integration and stability of the graphene based devices are provided. These results indicate the potential of graphene for low cost and high performance sensory applications and pinpoint the arguments to be addressed to bring highly reliable and advantageous graphene based devices into the semiconductor market.
- Chair of Electronic Devices