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Verma, Amit

Publications and source records attributed to Verma, Amit.

Data Analytics for Alloy Qualification

9-12% Cr-steels are used as structural material in boiler and turbine (rotor/casing) applications, with a power plant designed to operate for at least 30 years at either sub- or supercritical conditions (high pressure and temperature). In high-efficiency power plants, some components must withstand high stress and temperature for 100,000 h of operation without failure (Abe, 2011; Abe, et al., 2008; Coleman & Newell Jr., 2007; Viswanathan, 1989; Viswanathan & Bakker, 2001; Viswanathan & Bakker, 2001; Masuyama, 2001). Motivation for this project came from the need for rigorous and time-consuming alloy qualification (standardization) process, for crucial applications. Material scientists have traditionally manipulated alloying element composition and thermomechanical processing to achieve specific mechanical properties in alloys. The goals of this work were to develop a systematic and data-centric framework for analysis and characterization of materials information, to explore new alloy compositions and/or processing, and to better predict stress-rupture lifetime and other mechanical properties. A small subset of carbon steels with similar ferritic or martensitic lath microstructure (and average prior austenite grain size) was chosen for this analysis.

36 MATERIALS SCIENCE↗

Large electron concentration modulation using capacitance enhancement in SrTiO{sub 3}/SmTiO{sub 3} Fin-field effect transistors

Solid-state modulation of 2-dimensional electron gases (2DEGs) with extreme (∼3.3 × 10{sup 14 }cm{sup −2}) densities corresponding to 1/2 electron per interface unit cell at complex oxide heterointerfaces (such as SrTiO{sub 3}/GdTiO{sub 3} or SrTiO{sub 3}/SmTiO{sub 3}) is challenging because it requires enormous gate capacitances. One way to achieve large gate capacitances is by geometrical capacitance enhancement in fin structures. In this work, we fabricate both Au-gated planar field effect transistors (FETs) and Fin-FETs with varying fin-widths on 60 nm SrTiO{sub 3}/5 nm SmTiO{sub 3} thin films grown by hybrid molecular beam epitaxy. We find that the FinFETs exhibit higher gate capacitance compared to planar FETs. By scaling down the SrTiO{sub 3}/SmTiO{sub 3} fin widths, we demonstrate further gate capacitance enhancement, almost twice compared to the planar FETs. In the FinFETs with narrowest fin-widths, we demonstrate a record 2DEG electron concentration modulation of ∼2.4 × 10{sup 14 }cm{sup −2}.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗