Backscattering and common-base current gain of the Graphene Base Transistor (GBT)

In this paper, we investigate electron transport and electron scattering in the insulators of the Graphene Base Transistor (GBT) by means of a Monte Carlo transport model. We focus on electron backscattering in the base-collector insulator as the possible root cause of the large experimental base current and small measured common-base current gain (\u3b1F) of GBTs. Different GBT structures have been simulated and the impact of the scattering parameters on the base current is analyzed. Simulated backscattering-limited \u3b1F values are found to be much higher than available experimental data, suggesting that state-of-the-art technology is still far from being optimized. However, those simulated \u3b1F values can be low enough to limit the maximum achievable GBT performance

Electrical Compact Modeling of Graphene Base Transistors

Following the recent development of the Graphene Base Transistor (GBT), a new electrical compact model for GBT devices is proposed. The transistor model includes the quantum capacitance model to obtain a self-consistent base potential. It also uses a versatile transfer current equation to be compatible with the different possible GBT configurations and it account for high injection conditions thanks to a transit time based charge model. Finally, the developed large signal model has been implemented in Verilog-A code and can be used for simulation in a standard circuit design environment such as Cadence or ADS. This model has been verified using advanced numerical simulation

On the Adequacy of the Transmission Line Model to Describe the Graphene-Metal Contact Resistance

The contact-end-resistance (CER) method is applied to transfer length method structures to characterize in-depth the graphene-metal contact and its dependence on the back-gate bias. Parameters describing the graphene-metal stack resistance are extracted through the widely used transmission line model. The results show inconsistencies which highlight application limits of the model underlying the extraction method. These limits are attributed to the additional resistance associated with the p-p+ junction located at the contact edge, that is not part of the conventional transmission line model. Useful guidelines for a correct application of the extraction technique are provided, identifying the bias range in which this additional resistance is negligible. Finally, the CER method and the transmission line model are exploited to characterize the graphene-metal contacts featuring different metals. \ua9 2012 IEEE

Explanation of the Charge Trapping Properties of Silicon Nitride Storage Layers for NVMs-Part II: Atomistic and Electrical Modeling

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Going Ballistic: Graphene Hot Electron Transistors

This paper reviews the experimental and theoretical state of the art in ballistic hot electron transistors that utilize two-dimensional base contacts made from graphene, i.e. graphene base transistors (GBTs). Early performance predictions that indicated potential for THz operation still hold true today, even with improved models that take non-idealities into account. Experimental results clearly demonstrate the basic functionality, with on/off current switching over several orders of magnitude, but further developments are required to exploit the full potential of the GBT device family. In particular, interfaces between graphene and semiconductors or dielectrics are far from perfect and thus limit experimental device integrity, reliability and performance

Revised analysis of Coulomb scattering limited mobility in biaxially strained silicon MOSFETs

We present a simulation study of the dependence of the Coulomb limited mobility on the biaxial strain in -type (001) Si MOSFETs. By using a model based on the Momentum Relaxation Time (MRT) approximation, we first reproduce fairly well a wide set of published experiments, then we use our simulations to explain the dependence on the strain of the mobility limited by interface states and substrate impurities. Differently from the experiments, the MRT approach allows us to study the different mobility components without resorting to the Matthiessen\u2019s rule, which can lead to large errors in the extrated mobility. Simulations indicate that the strain reduces the interface state limited mobility, while it leaves essentially unchanged the substrate impurity limited mobility