Resistively Coupled Single-electron Transistor Research Articles

Capacitively- and resistively-coupled single-electron transistor

Single-electron transistor (SET) which operates as capacitively-coupled SET (C-SET) and resistively-coupled SET (R-SET) was fabricated using two-dimensional electron gas and metal Schottky gates. The Coulomb diamonds of both C-SET and R-SET were observed at ⋍ 30 mK. The observed Coulomb diamond of R-SET is shifted along the gate-voltage axis, although it should not be shifted in the theoretical prediction.

Resistively coupled single-electron transistor using tunnel gate resistor

A resistively coupled single-electron transistor (R-SET) was fabricated using a modulation-doped heterostructure and metal Schottky gates, and measured at low temperature. Currents of R-SET with tunnel gate resistor were calculated using the orthodox theory. It is shown that the R-SET with tunnel gate resistor has quite similar properties to the originally proposed R-SET.

Transport Properties of a Resistively-Coupled Single-Electron Transistor

A resistively-coupled single-electron transistor (R-SET), whose gate was a tunnel resistor, was fabricated using a modulation-doped GaAs/AlGaAs heterostructure and metal Schottky gates. Observed current-voltage characteristics show the Coulomb diamonds which are predicted for an R-SET. This means that the tunnel resistor can be used as an R-SET gate.

Coulomb Blockade in Resistively Coupled Single-Electron Transistor: Dependence on Bias Conditions

We have measured resistively coupled single electron transistors under two bias conditions: asymmetric and symmetric. We observed a characteristic Coulomb blockade pattern whose shape is significantly different for the two cases. Our simulations based on the orthodox theory of single-electron tunneling are in good qualitative agreement with the experimental data.

Metallic resistively coupled single-electron transistor

We have fabricated and measured transport properties of resistively coupled single-electron transistors (R-SETs). In our version, a chromium thin-film resistive strip served as a gate and was connected directly to a mesoscopic island formed between two ultrasmall Al/AlOx/Al tunnel junctions. In current–voltage-gate voltage dependences of the R-SETs, a characteristic Coulomb blockade pattern was observed. Our simulations based on the orthodox theory of single-electron tunneling are in good qualitative agreement with the experimental data and indicate excessive electron temperature of the devices.

Implementation of Single-Electron Transistor with Resistive Gate

We have fabricated and measured a resistively coupled single electron transistor (R-SET). In our implementation, a chromium thin-film resistive gate was connected directly to a mesoscopic island formed between two ultrasmall Al/AlOx/Al tunnel junctions. The transistor was fabricated by electron beam lithography using the suspended bridge technique. We have measured the current-voltage-gate voltage dependences of the R-SET and observed a characteristic Coulomb blockade pattern. Our simulations based on the orthodox theory of single electron tunneling show good qualitative agreement with the experimental data.

Theoretical analysis of the resistively coupled single-electron transistor

The operation of the resistively coupled single-electron transistor (R-SET) is studied quantitatively. Due to the Nyquist noise of the coupling resistance, degradation of the R-SET performance is considerable at temperatures T as small as 10−3e2/C (where C is the junction capacitance) while the voltage gain becomes impossible at T≳10−2e2/C.

Complementary Digital Logic Using Resistively Coupled Single-Electron Transistor

A new complementary digital logic based on resistively coupled single-electron transistors (R-SET) was proposed and its basic characteristics were numerically analyzed using the Monte Carlo method. The proposed logic has a logic threshold independent of background polarization charges which induce crucial problems in logic operation in the case of a capacitively coupled logic. In addition, the proposed complementary R-SET logic has larger output voltage swing and better logic level stability than those of a conventional resistance-load R-SET logic. The stability of the logic level of the complementary R-SET logic was investigated by calculating the data retention time of flip-flop circuits, and its dependence on temperature and shot noise was examined. For stable operation of the flip-flop circuit, estimated optimal operation temperature and switching delay time are e2/80C tk B and 1500 R tC t, respectively, where C t and R t are capacitance and resistance of the tunnel junction.

1-D array implementation of the resistively-coupled single-electron transistor

The authors fabricated and tested the first version of the resistively coupled single-electron transistor (R-SET) based on the correlated transfer of single electrons in ultrasmall junctions. In this version, a one-dimensional array of 80*80 nm/sup 2/ Al/Al/sub x/O/sub y//Al junctions served as a resistor for transmission of the signal to the middle electrode of a pair of similar junctions. Of three tested R-SETs, all exhibited a real power gain, and one device showed a DC voltage gain of 0.85. The data are found to be in reasonable agreement with numerical simulations based on the orthodox theory of correlated tunneling taking into account the superconductivity of aluminum electrodes.