Presence Of Negative Differential Resistance Research Articles

On the relationship between negative differential resistance and stability for nonlinear one-ports

We give results for nonlinear one-ports regarding the relationship between negative differential resistance at a particular dc operating point and the stability of that operating point. In particular, we illustrate that the presence of negative differential resistance does not necessarily imply instability for any positive resistive port termination hut that it does imply instability for either an open-circuit or a short-circuit termination.

Observation of negative differential resistance in tunneling spectroscopy of MoS2 with a scanning tunneling microscope

A scanning tunneling microscope has been used for imaging and tunneling spectroscopy of 2Hb–MoS2 in ultrahigh vacuum. Atom-resolved images obtained in three distinct imaging modes–measuring z at constant current, barrier height at constant current, and current at constant z–are presented. Current–voltage (I–V) tunneling spectra reveal the occasional presence of negative differential resistance. Possible origins of the effect are discussed. Convolution of the sample energy density of states (DOS) with a contamination-induced peak in the tip DOS is the probable cause. Other mechanisms that may be active include charging of electron traps in the barrier or on the tip, and resonant tunneling in a double-barrier quantum well structure resulting from layer separation in the MoS2 crystal.

In/sub 0.52/Al/sub 0.48/As/In/sub x/Ga/sub 1-x/As (0.53>or=x>or=0.70) lattice-matched and strained heterostructure insulated-gate FETs

The DC and microwave properties of In/sub 0.52/Al/sub 0.48/Al/In/sub x/Ga/sub 1-x/As (0.53<or=x<or=0.70) heterostructure insulated gate field-effect transistors (HIGFETs) with a quantum well channel design are presented. DC and microwave transconductances (g/sub m/) are enhanced as the In content is increased in the InGaAs channel. An intrinsic microwave g/sub m/ value of 428 mS/mm and a K-factor of 1140 mS/mm-V have been obtained for 1.0- mu m gate length with the 65% In channel devices. The sheet charge density, drift mobility, transconductance, current-gain cutoff frequency (f/sub T/), and maximum oscillation frequency (f/sub max/) all show a continuous improvement up to 65% In content (f/sub T/=22.5 GHz with 53% and f/sub T/=27 GHz with 65% In; the corresponding f/sub max/ change is from 6.5 to 8 GHz). The device performance degrades as the In content is increased to 70%. DC and microwave characteristics show the presence of negative differential resistance (NDR) up to 2.7 GHz.<<ETX>>