Browse Prior Art Database

Method of Extracting Tunneling Coefficient via Capacitance Measurement in Tunneling Field Effect Transistors (TFETs)

IP.com Disclosure Number: IPCOM000241934D
Publication Date: 2015-Jun-09
Document File: 3 page(s) / 48K

Publishing Venue

The IP.com Prior Art Database

Abstract

Disclosed is a method to determine the tunneling coefficients in Tunnel Field Effect Transistors (TFETs) using standard electrical measurements; this calculates the quantum mechanical tunneling rate from capacitance measurements.

This text was extracted from a PDF file.
This is the abbreviated version, containing approximately 51% of the total text.

Page 01 of 3

Method of Extracting Tunneling Coefficient via Capacitance Measurement in Tunneling Field Effect Transistors (TFETs)

Integrated circuits consume a large quantity of power due to static power dissipation from the billions of Metal Oxide Semiconductor Field Effect Transistors (MOSFETs) in it. There is a continuous search for an alternative transistor design with extremely low off-state leakage current and a moderate to high "ON" state current.

A Tunneling Field Effect Transistor (TFET) offers the ability to achieve low-power electronic devices. A TFET exploits quantum mechanical tunneling of carriers instead of diffusion, as in MOSFET devices. A crucial physical quantity for a TFET device is the tunneling rate of carriers (i.e. Transmission coefficient, Ton). A device designer must know the accurate value of the tunneling coefficient for device design and optimization. Both the "ON" and "OFF" state currents of a TFET are strongly dependent on this tunneling coefficient.

The novel contribution is a method to extract the tunneling coefficient from electrical measurement (i.e. capacitance-voltage). In addition, the solution presents a method to remove the asymmetric overlap capacitance, which typically masks the accurate extraction of the Ton.

The disclosed method describes a direct measurement technique to accurately determine the tunneling coefficient. The novel contribution is a method to determine the tunneling coefficients using standard electrical measurements; this calculates the quantum mechanical tunneling rate from capacitance measurements. The disclosure proposes structures consist of an array of TFETs and an array of equivalent Positive channel Field Effect Transistors (PFETs) sharing similar process steps. The method measures source-gate and drain-gate capacitance of the array of TFETs and PFETs and removes bias-dependent overlap capacitance of TFETs. The extraction of the quantum mechanical tunneling rate is based on ratios of source and drain capacitances.

Figure 1: Equation 1: The approximate expression of the "ON" current of a TFET

In the equation presented in Figure 1:


 J is the current density


 n is the average carrier density


 q is the electronic charge


 Ve is the average velocity of carrier


 Te is the tunneling coefficient through the barrier of a conventional TFET

The exact knowledge of Te is crucial to know the output current of a TFET. Te is, in general, gate-voltage dependent. To extract the Te, as a function of gate voltage, the method analyzes a small signal circuit of TFET. (Figure 2)

1


Page 02 of 3

Figure 2: Schematic of equivalent small-signal circuits for TFETs considered here

Figure 2 s...