Numerical Simulation of Negative Differential Resistance Characteristics in Si/Si1- χGeχRTD at Room Temperature

Negative differential resistance (NDR) characteristics in the current-voltage curve of a p-type Si/Si1-χGeχresonant tunnelling diode (RTD) are simulated with the quantum hydrodynamic (QHD) model. An integrated difference scheme including Schafetter-Gummel (SG) method, second upwind method and second-order central difference method is used to discretize the QHD equations, which maintains both accuracy and stability. This work is the first to simulate hole transport in RTD using the QHD model. Investigations of some structure modifications have been carried out. Analysis of the results indicates that both quantum barrier thickness and hole effective mass have an impact on NDR characteristics for Si/Si1-χGeχRTD. The simulated peak-to-valley current ratio (PVCR) of 1.14 at T=293K agrees quantitatively with the experimental result when x=0.23.