Reinaldo A. Vega

Study of Random Dopant Fluctuation Effects in Germanium-Source Tunnel FETs

The effects of random dopant fluctuations (RDFs) on the performance of Germanium-source tunnel field-effect transistors (TFETs) is studied using 3-D device simulation. The RDF in the source region is found to have the most impact on threshold voltage variation (σ<i>V</i>_TH) if the source is moderately doped (10¹⁹ cm^-3) such that vertical tunneling within the source is dominant. If the source is heavily doped (10²⁰ cm^-3) such that lateral tunneling from the source to the channel is dominant, the impact of RDF in the channel region is also significant. RDF-induced threshold voltage variation (σ<i>V</i>_TH) for an optimally designed Ge-source TFET is relatively modest (σ<i>V</i>_TH <; 20 mV at <i>Lg</i> = 30 nm), compared with a MOSFET of similar gate length. Supply voltage scaling is not beneficial for reducing TFET σ<i>V</i>_TH.

Comparative Study of FinFET Versus Quasi-Planar HTI MOSFET for Ultimate Scalability

The FinFET is compared against the quasi-planar trigate bulk MOSFET with high-permittivity (high- k) dielectric trench isolation (HTI MOSFET) for low-standby-power applications, at dimensions near the end-of-roadmap (11-nm half-pitch). It is found that the optimal transistor structure depends on the fin aspect ratio (AR) and the HTI dielectric constant εHTI: for sufficiently high εHTI, the HTI MOSFET can provide comparable or lower delay as the FinFET, for AR up to ~2.5. Thus, the development of high-k dielectric and/or high-AR fin formation technologies will ultimately determine which transistor design is more advantageous.

Understanding short channel mobility degradation by accurate external resistance decomposition and intrinsic mobility extraction

An intrinsic short channel mobility extraction method is proposed by measuring two short-channel devices with different channel lengths and the same source/drain and contact geometry. The constant and dynamic components of external resistance are separated. Short-channel mobility degradation is observed and its origin is studied. The possible causes of the halo doping and the non-uniformity of the inversion layer charge are accounted for. The weaker temperature dependence of short channel devices indicates that the short channel mobility degradation may result from some combination of defect-induced and Coulomb-induced scattering near the S/D regions, differing in severity between NFETs and PFETs which employ, respectively, ion implant and embedded epitaxy as the primary component of S/D design.

Technology viable DC performance elements for Si/SiGe channel CMOS FinFTT

Low Ge content SiGe-based CMOS FinFET is one of the promising technologies [1-2] offering solutions for both high performance and low power applications. In this paper, we established a competitive SiGe-based CMOS FinFET baseline and examined various elements for high performance offering. The performance elements in gate stack, channel doping, contact resistance, and junction have been explored to provide a cumulative 20% / 25% (n/pFET) performance enhancement. These elements provide a viable path towards performance enhancement for future technology nodes.

An interdigitated electrode detector for the identification of a single specific DNA molecule fragment

The detection of a single specific DNA molecule fragment will allow for the identification of bacteria and viruses that could be harmful if not detected quickly. DNA probes attached to the sensor electrodes have a specific molecular sequence that results in a billion to one or better probability that any DNA that hybridizes with the probe is the DNA to be detected. The DNA is coated with a metal, resulting in a large decrease in the measured electrical resistance between the sensor electrodes. Thus the electrical detection of a specific single DNA molecule fragment is very easy.