Passivation controlled field effect mobility in 2D semiconductor based FET devices for high performance logic circuit development on flexible platform

The family of two-dimensional transition metal dichalcogenides (TMDs) is a fertile ground for cultivating fundamental material science and emergent applications in high-performance electronics. In TMD based micro and nanoelectronic devices, passivation and doping strategies needs comprehensive study to optimize charge carrier mobility, operating points, hysteresis and long-term device stability. For devices on flexible platform, additional issues like mechanical flexibility of the passivation layer and lower thermal treatments also need considerations. In the current work, we will present our results on impact of different passivation methods, compatible with flexible platform, on the performance of CVD grown MoS2 based FET devices. Our results clearly demonstrate that only through control of passivating layer and thermal annealing treatments, it is possible to modify the field effect mobility of the devices by 3 orders of magnitude. The best mobility value arises due to strong n-doping arising from ALD grown Al2O3 layer, while alternate layers of Parylene N and Al2O3 gives best performance in terms of hysteresis and passivation, together with a positive shift in the operating point. This study provides potential direction for low thermal budget, high mechanical flexibility strategies to control carrier doping and prevent challenges like poor yield, performance degradation, irreproducibility and instability of TMD based fully integrated circuits on flexible platform.