Abstract: An n-channel metal-insulator-semiconductor field-effect transistor (MISFET) that exhibits negative differential resistance in its output characteristic (drain current as a function of drain voltage) is disclosed. The MISFET includes a dynamically variable and reversible threshold voltage which is controlled by a source-drain bias. A channel region of the MISFET is doped so as to enhance an electric field associated with the source-drain bias, and thus cause charge carriers to tunnel out of the channel and into a trapping region. A net charge in the trapping region results from the source-drain bias which can be used as an additional control mechanism for conduction in the MISFET.

Abstract: A semiconductor manufacturing process is disclosed that is suitable for making both negative differential resistance (NDR) and non-NDR devices at the same time. An NDR process is thus integrated within a conventional CMOS process so that compatibility with existing fabrication procedures is maintained. In addition, many of the NDR process steps and non-NDR process steps are shared in common to form features of such devices at the same time.

Abstract: A process for operating a dual mode FET and a logic circuit to include a negative differential resistance (NDR) characteristic is disclosed. In a FET embodiment, an NDR characteristic is selectively enabled/disabled by biasing a body contact, thus permitting a dual behavior of the device. Larger collections of such FETs can be synthesized to form dual mode logic circuits as well, so that a single circuit can perform more than one logic operation depending on whether an NDR mode is enabled or not.

Abstract: A method of making an n-channel metal-insulator-semiconductor field-effect transistor (MISFET) that exhibits negative differential resistance in its output characteristic (drain current as a function of drain voltage) is disclosed. By implanting ions into a substrate that is later thermally oxidized, a number of temporary charge trapping sites can be established above a channel region of a transistor. The channel is also heavily doped, so that a strong electrical field can be generated to accelerate hot carriers into the temporary charge trapping sites. The insulating layer formed during the oxidation step is made sufficiently thick to prevent quantum tunnelingo of the hot carriers into a gate electrode. Other suitable and conventional processing steps are used to finalize completion of the fabrication of the NDR device so that the entire process is compatible and achieved with CMOS processing techniques.

Abstract: An active negative differential resistance element (an NDR FET) and a memory device (such as an SRAM) using such elements is disclosed. Soft error rate (SER) performance for NDR FETs and such memory devices are enhanced by adjusting a location of charge traps in a charge trapping layer that is responsible for effectuating an NDR behavior. Both an SER and a switching speed performance characteristic can be tailored by suitable placement of the charge traps.

Abstract: An electronic device includes a FET that is capable of operating in a negative differential resistance mode as well as in a conventional FET mode. The selection of the mode can be accomplished by providing a control signal to a body terminal of the FET as needed for a particular application. By providing two different operating modes a multi-function logic gate is effectuated that can perform two or more different logical functions on an input signal. Furthermore the device can be used as an element of a new logic family and synthesized into suitable configurations so that more sophisticated and complex functions are achieved with increased density, lower power, etc. over conventional semiconductor FETs.

Abstract: An n-channel metal-insulator-semiconductor field-effect transistor (MISFET) that exhibits negative differential resistance in its output characteristic (drain current as a function of drain voltage) is disclosed. For a fixed gate voltage, the MISFET channel current, which flows between the drain and source terminals of the transistor, firstly increases as the drain-to-source voltage increases above zero Volts. Once the drain-to-source voltage reaches a pre-determined level, the current subsequently decreases with increasing drain-to-source voltage. In this region of operation, the device exhibits negative differential resistance, as the drain current decreases with increasing drain voltage. The drain-to-source voltage corresponding to the onset of negative differential resistance is also tunable. In addition, the drain current and negative differential resistance can be electronically tailored by adjusting the gate voltage.

Abstract: A charge trapping structure for use with an n-channel metal-insulator-semiconductor field-effect transistor (MISFET) is disclosed. A dielectric layer is formed close to a channel region of the MISFET, and includes a number of trapping sites which are arranged and have a concentration sufficient to temporarily store energetic electrons induced by an electric field to move from the channel into the trapping sites. The trapped electrons set up a counter field that depletes the channel of carriers, and as a bias voltage across the channel increases, the device exhibits negative differential resistance (NDR). The charge trapping structure, as well as the rest of the device, are formed using conventional CMOS processing techniques.