Absolute Negative Resistance Induced by Directional Electron-Electron Scattering in a Two-Dimensional Electron Gas

A three-terminal device formed by two electrostatic barriers crossing an asymmetrically patterned two-dimensional electron gas displays an unusual potential depression at the middle contact, yielding absolute negative resistance. The device displays momentum and current transfer ratios that far exceed unity. The observed reversal of the current or potential in the middle terminal can be interpreted as the analog of Bernoulli’s effect in a Fermi liquid. The results are explained by directional scattering of electrons in two dimensions.

Figure 1

(a) The layout of the device. The gray shaded area is the mesa that restricts the 2DEG conductor. Dimensions shown in microns. The dark lines are metal gates forming the electrostatic barriers. Arrows indicate the direction of electron current through the leads. (b) The energy diagram for the device. Solid and dashed lines represent the conduction band and Fermi energy levels, respectively. Electrons are injected from negatively biased ($V_E$) emitter ($E$) into the base ($B$) and transported to collector ($C$).

Figure 2

Measured currents through three terminals, $I_E$, $I_C$ and $I_B$ versus collector gate voltage, $V_{\mathrm{GC}}$; $V_{\mathrm{GE}}=-540\mathrm{mV}$, $V_E=-25\mathrm{mV}$, $V_B=V_C=0$. $T=4.2\mathrm{K}$; inset represents the measurement configuration. Curve labeled as $G_C$ is the measured equilibrium conductance of the collector barrier for $V_C=1\mathrm{mV}$ (after subtracting the lead resistances), $V_{\mathrm{GE}}=V_E=V_B=0$. ${\phi }_C$ is the calculated collector barrier height from the equilibrium conductance data according to Eq. (1).

Figure 3

(a) The dc current transfer ratio $\alpha =|I_C/I_E|$ versus emitter voltage, $V_E$, as the emitter barrier is increased in steps, $V_{\mathrm{GE}}=-550\mathrm{mV},-555\mathrm{mV},\dots ,-700\mathrm{mV}$, $V_{\mathrm{GC}}=-330\mathrm{mV}$ (from lowest to highest trace, respectively). (b) The momentum transfer ratio, $\gamma$ versus injected power calculated from data in (a) (solid lines) and corresponding $V_E$ vs $P_{\mathrm{in}}$ curves (dashed lines).

Figure 4

(a) Base voltage, $V_B$, versus $V_E$ for the same set of $V_{\mathrm{GE}}$, $V_{\mathrm{GC}}$ values as in Fig. 3a. Inset shows the measurement configuration. (b) Three-terminal resistance, $R_{CB}=(V_B-V_C)/I$ and current, $I=I_E=-I_C$ versus $V_E$ at various temperatures. $V_{\mathrm{GE}}=-550\mathrm{mV}$, $V_{\mathrm{GC}}=-340\mathrm{mV}$.