Performance Limit Projection of Germanane Field-Effect Transistors

Here we explore the performance limit of monolayer germanane (GeH) field-effect transistors (FETs). We first plotted an electronic band structure of GeH using density functional theory and then tight-binding parameters were extracted. Device characteristics of GeH FETs are investigated using rigorous self-consistent atomistic quantum transport simulations within tight-binding approximations. Our simulation results indicate that GeH FETs can exhibit exceptional on-state device characteristics, such as high I_on (>2 mA/μm) and large g_m (7 mS/μm) with V_DD = 0.5 V due to the very light effective mass of GeH (0.07m₀), while maintaining excellent switching characteristics (SS 64 mV/dec). We have also performed a scaling study by varying the channel length, and it turned out that GeH FET can be scaled down to 14-nm channel without facing significant short channel effects but it may suffer from large leakage current at the channel length shorter than 10 nm. Finally, we have benchmarked GeH FET against MoS₂ counterpart, exhibiting better suitability of GeH device for high-performance applications compared with MoS₂ transistors.