2021 New's Items

Inhibited nonradiative decay at all exciton densities in monolayer semiconductors

Kim H
Uddin SZ
Higashitarumizu N
Rabani E
Javey A
2021

Most optoelectronic devices operate at high photocarrier densities, where all semiconductors suffer from enhanced nonradiative recombination. Nonradiative processes proportionately reduce photoluminescence (PL) quantum yield (QY), a performance metric that directly dictates the maximum device efficiency. Although transition metal dichalcogenide (TMDC) monolayers exhibit near-unity PL QY at low exciton densities, nonradiative exciton-exciton annihilation (EEA) enhanced by van-Hove singularity (VHS) rapidly degrades their PL QY at high exciton densities and limits their utility in...

Actively variable-spectrum optoelectronics with black phosphorus

Kim H
Uddin SZ
Lien DH
Yeh M
Azar NS
Balendhran S
Kim T
Gupta N
Rho Y
Grigoropoulos CP
Crozier KB
2021

Room-temperature optoelectronic devices that operate at short-wavelength and mid-wavelength infrared ranges (one to eight micrometres) can be used for numerous applications1,2,...

Body-Biased Multiple-Gate Micro-Electro-Mechanical Relays

Ye ZA
Almeida SF
Sikder U
Hu X
Esatu TK
Le K
Liu TK
2021

Micro-electro-mechanical relays with multiple gate electrodes (i.e., multiple input voltage signals), operated with a tunable body bias voltage, are investigated for more compact and energy-efficient implementation of digital logic circuits. Specifically, a relay design with three gate electrodes of equal area is demonstrated to be capable of performing different digital logic functions for the same input operating voltage (VDD), by adjusting the body bias voltage. Since the lower limit for VDD is equal to the switching hysteresis voltage (VH), the magnitude of VH is investigated for...

Design optimization of sub-5 nm node nanosheet field effect transistors to minimize self-heating effects

Ding F
Wong H
Liu TK
2021

In this work, self-heating effects (SHE) in nanometer-scale metal-oxide-semiconductor field-effect transistor structures—namely, FinFETs (FFs), nanosheet gate-all-around FETs (NSFs), and nanowire gate-all-around FETs (GAAFs)—are investigated via three-dimensional device electrothermal simulations using technology computer-aided design software tools. Initially, transistor design parameter values are set so that their on-state currents are similar for the same operating voltage (VDD). It is found that NSFs and GAAFs are more susceptible to SHE and that...

Design Technology Co-Optimization for Back-End-of-Line Nonvolatile NEM Switch Arrays

Tatum LP
Sikder U
Liu TK
2021

Design tradeoffs for vertically oriented nonvolatile (NV) nano-electro-mechanical (NEM) switches implemented using multiple interconnect layers in a 5-nm-generation CMOS back-end-of-line (BEOL) process are investigated via 3-D device simulation. Programming pulse voltage and width operating windows are identified for avoiding catastrophic pull-in. The simulation results indicate that sub-20-ns programming delay is possible with programming voltages compatible with standard input-output (I/O) CMOS circuitry, and that the write energy of an NV-NEM bit-cell will be less than 5 aJ. A...

Simulation-Based Study of High-Permittivity Inserted-Oxide FinFET With Low-Permittivity Inner Spacers

Wu Y.
Chiang M.
Chen J.
Liu T.
2021

A high-permittivity (high- k ) inserted-oxide FinFET (iFinFET) structure with low-permittivity inner spacers is proposed for CMOS transistor scaling to the 3-nm technology node and beyond. The process to fabricate an iFinFET is similar to the process to fabricate a nanosheet field-effect transistor (NSFET); no additional lithography masks are needed. Unlike the NSFET and the nanowire field-effect transistor (NWFET), which each require significant spacing between the...