Highly functional tunnelling devices integrated in 3D

Abstract

SUMMARYWe present a new technology for integrating tunnelling devices in three dimensions. These devices are fabricated by the combination of the growth of semiconductor heterostructures with the controlled introduction of metallic elements into an epitaxial layer by an overgrowth technique. First, we use a new type of tunnelling transistor, namely a resonant-tunnelling permeable base transistor. A simple model based on a piece-wise linear approximation is used in Cadence to describe the current-voltage characteristics of the transistor. This model is further introduced into a small signal equivalent circuit in order to optimize the performance of the device. In addition to the tunnelling structure below the grating, these transistors may be integrated in 3D by the introduction of another tunnelling structure directly over the metal grating. In the integrated device structure, the gate acts simultaneously on both tunnelling structures and the obtained characteristics are the result of the interplay between the two tunnelling structures and the gate. An equivalent circuit model is developed and we show how this interaction in uences the current-voltage characteristics. The gate may be used to adjust the peak voltage of certain peaks in a controlled fashion, which creates a highly functional tunnelling device. These results show the need for a strong interaction between the development of circuit models and processing technology to develop new nano-electronic devices and circuits.

Generalization of the jump postulate and Brayton‐Moser's mixed potential for the analysis of RTD circuits

“…This statement applies to all circuits for which a MPF can be specified ( [24] and [34]) and whose dynamic equations represent a gradient system [36]. Therefore, the generalized jump postulate holds for circuits including only one kind of energy storage element yielding only one of both equations from (3). Besides the series connected N-type nonlinearities treated in this paper, parallel connected S-type nonlinearities are covered in the same way.…”

“…The analysis of circuits with series connected resonant tunneling diodes (RTDs) is an essential topic in modern nanoelectronic technology (cf. [1][2][3]). Because RTDs belong to the electronic solid state devices with the highest ever measured operating frequency [4], RTD-based logic circuits can be regarded as possible post CMOS integrated systems [5].…”

Circuits and devices with integrated VFETs and RTDs

“…We have very recently been integrating two RTDs in a VFET structure by the introduction of a double banier resonant tunnelling structure into the overgrowth over a metal grating [7]. In this structure the grate acts on both diodes simultaneously, which results in a rather complex I-V V -207 characteristics.…”