Si–Ge based vertical tunnel field-effect transistor of junction-less structure with improved sensitivity using dielectric modulation for biosensing applications

A dielectric modulation strategy for gate oxide material that enhances the sensing performance of biosensors in junction-less vertical tunnel field effect transistors(TFETs)is reported.The junction-less technique,in which metals with specific work functions are deposited on the source region to modulate the channel conductivity,is used to provide the necessary doping for the proper functioning of the device.TCAD simulation studies of the proposed structure and junction structure have been compared,and showed an enhanced rectification of 10^(4) times.The proposed structure is designed to have a nanocavity of length 10 nm on the left-and right-hand sides of the fixed gate dielectric,which improves the biosensor capture area,and hence the sensitivity.By considering neutral and charged biomolecules with different dielectric constants,TCAD simulation studies were compared for their sensitivities.The off-state current IOFFcan be used as a suitable sensing parameter because it has been observed that the proposed sensor exhibits a significant variation in drain current.Additionally,it has been investigated how positively and negatively charged biomolecules affect the drain current and threshold voltage.To explore the device performance when the nanogaps are fully filled,half filled and unevenly filled,extensive TCAD simulations have been run.The proposed TFET structure is further benchmarked to other structures to show its better sensing capabilities.

Enhanced visible green and 1.5μm radiative emission of Er^(3+)ions in Li_(2)O-PbO-Al_(2)O_(3)-B_(2)O_(3) glasses for photonic applications

A series of Er^(3+)ions doped lithium lead alumino borate(LiPbAlB)glasses were synthesized via melt quench method and their structural,physical and optical properties were studied.Judd-Ofelt theory in correlation with the emission and absorption profiles was performed for the measurement of various radiative parameters for different transitions of Er^(3+)doped glasses.The as-prepared glasses show deep green(550 nm)as well as NIR(1532 nm)emission at 380 and 980 nm excitation wavelengths,respectively.The intensity of emission spectra increases with Er^(3+)ions concentration up to 1.5 mol%and beyond quenching is observed.The Dexter theory applied to the emission profiles reveals the interaction between Er^(3+)ions as dipole-dipole in nature.CIE color coordinates are found to fall in the green region of the visible spectrum.It is observed that 1.5 mol%of Er^(3+)ions concentration is optimum to exhibit the maximum quantum efficiency,branching ratios,gain bandwidth,emission cross-section,gain crosssection and aptly suitable for visible and NIR photonic applications.