Integrated Optoelectronics with van der Waals Materials

This thesis studies the novel optoelectronic operation principles and functions with vdW material integrated devices. The main study outputs include optically configurable AAT/Bi-AAT photoresponses, a reconstructive spectroscopic material identification based on a semiconductor/metal heterostructure, and a nanostructured InSe waveguide photodetector. The first part of this thesis provides an overview of the vdW material integrated optoelectronics. The second part introduces the basis of vdW materials, and the principles of photodetection studied in this thesis. The advanced vdW material integrated optoelectronic devices are reviewed, especially the devices on the optical waveguide platform. The third part reviews the microfabrication techniques utilised in this work, and the characterisation methods such as electrical and optoelectronic measurement setups. The fourth part includes an optically configurable AAT/bi-AAT photoresponse. The AAT behaviour results from charge trapping and detrapping processes, assisted by manually introduced trap state. A symmetric device configuration is employed to achieve the AAT photoresponse. Two sources of carrier detrapping lead to wavelength-dependent AAT/bi-AAT photoresponses. The demonstration introduces optical wavelength as a trigger for advanced photoresponses. The fifth part presents a computational reconstructive wavelength meter, leveraging a configurable semiconductor/metal heterostructure that has both VDS and VGS tunable wavelength-dependent photoresponses. The feature of high peak-wavelength accuracy is further conducted for complex spectrum inputs for material identification. The sixth part investigates two optoelectronic devices with the optical waveguide platform, including the reuse of the reconstructive wavelength meter, and a nanostructured InSe waveguide photodetector that enables light direct insertion and out-of-plane dipole-assisted light absorption. Finally, the studies in this thesis are summarised and concluded. The possible optimisations and outlook are presented.