Artificial Synaptic Floating Gate Transistors Based on Hybrid Organic-Inorganic Perovskites.

The ascent of artificial intelligence and the increasing demand for clean energy technologies in Europe has given rise to a pertinent need for modern computing systems with reduced energy consumption. Neuromorphic computing, inspired by the working of the human brain, constitutes a potential paradigm shift in low-energy computing. Floating gate synaptic transistors (FGTs), critical components in neuromorphic computing hardware, offer promising pathways to perform massively parallel computational tasks with ultralow energy consumption of 1-10 fJ/spike. Despite the promises of FGTs, several challenges related to limited control over the charge-trapping properties, morphology, and stability of the floating gate layer need to be addressed.

Hybrid organic-inorganic perovskites (HOIPs) have recently emerged as a photoactive floating-gate layer for use in FGTs. These have already shown outstanding characteristics towards their use in neuromorphic computing, such as an ultra-low energy use less than or comparable to the 1–10 fJ of energy consumed per synaptic spike by the nervous system. The majority of these studies so far have focused on nanoparticles of 3D HOIPs. However, these 3D HOIPs possess limited thermal-, photo- and moisture stability, which restricts the lifetime of the memory devices.

This PhD project will focus on the design & synthesis of 2D HOIPs with properties suitable for use as a photoactive floating gate layer. Only a handful of FGTs using 2D HOIPs as a floating gate layer have been reported to date, with promising results. In this project, we will go a step further in the design of the 2D HOIPs by incorporating tailored organic cations. The imomec group of IMEC has built up dedicated expertise over the years on this aspect for 2D HOIPs in various optoelectronic applications. Through the rational design of the organic cations, the charge trapping and de-trapping characteristics of the floating gate will be tuned and the stability of the hybrid material will be enhanced.

The candidate will perform the synthesis of novel organic cations and the corresponding 2D HOIPs, coupled with in-depth material characterization to obtain structure-property relationships. Next, the deposition process of thin films of the 2D HOIPs will be optimized toward a suitable morphology. Finally, the 2D HOIP layer will be implemented in a floating gate synaptic transistor device stack, and the synaptic transistor properties will be evaluated.

The project will be conducted as part of an interdisciplinary and multicultural team of highly skilled scientists who work toward the next generation of optoelectronic devices based on alternative (solution-processible) semiconductors. The research will be performed in the newly built ‘Science Tower’ at imo-imomec located on the campus of Hasselt University in Diepenbeek (Belgium). This facility contains state-of-the-art laboratories and equipment.