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This paper presents the peripheral circuitry for a multivalued static random-access memory (SRAM) based on 2-bit CMOS cross-coupled inverters using spatial wavefunction switched (SWS) field effect transistors (SWSFETs). The novel feature is a two quantum well/quantum dot channel n-SWSFET access transistor. The reduction in area with four-bit storage-per-cell increases the memory density and efficiency of the SRAM array. The SWSFET has vertically stacked two-quantum well/quantum dot channels between the source and drain regions. The upper or lower quantum charge locations in the channel region is based on the input gate voltage. The analog behavioral modeling (ABM) of the SWSFET device is done using conventional BSIM 3V3 device parameters in 90 nm technology. The Cadence circuit simulations for the proposed memory cell and addressing/peripheral circuitry are presented.

This paper presents experimental results of nMOS quantum dot gate field effect transistor (QDGFET) based inverter devices for SRAM devices. A three-state inverter device was fabricated and tested with Si/SiO₂ quantum dots. The work performed here builds off previous works performed with Si/SiO₂ dot-based inverters which used two layers of quantum dots. This research explores multi-state SRAM device operation. A three-state (Si QDs) and a four-state (Si and Ge QDs) inverter are described, and they will allow for multistate logic devices to be utilized in everyday logic chips, which will require less devices to perform the same tasks as conventional devices, double the capacity of the device, and require less power, which will generate less of a thermal footprint. The data of the Half Cell SRAM, comprised of one access transistor and an inverter along with a capacitor, is presented here.

This paper investigates the underlying physics of a SRAM device utilizing three-state Quantum Dot Gate (QDG) FETs by building up the physics from the general QDG-FET, its relation to the QDG-Inverter, and ultimately, the QDG-SRAM. The resulting equations from the exploration of the device physics were utilized to create a simulation within SIMULINK. From the simulation, it was found that in addition to being able to store the “1” and “0” states that are customary for an SRAM device, there is also the ability to store an intermediate state and a pseudo-state as a result of the intermediate state, allowing for the possibility of a 2-bit SRAM device in the same spatial constraints of a conventional SRAM unit cell. Additionally, the experimental results of the QDG-SRAM half-cell and the implications of utilizing a 4 state device to create either a 4 state SRAM cell or a 6 state SRAM cell with two pseudo-states are also discussed.

This paper describes fabrication of Quantum Dot Gate n-FETs using SiOx-cladded Si quantum dot self-assembled on the tunnel gate oxide. Experimental I-V characteristics exhibiting 4-states are presented. Simulation is presented for the operation of viable 4-state SRAMs using QDG-FETs.

This paper describes the fabrication of quantum dot gate (QDG) n-FETs using GeOx-cladded Ge quantum dot self-assembled on tunnel gate oxide. Experimental I–V characteristics exhibiting 4-states are presented. Simulations are presented for the operation of a viable 8-state SRAM using QDG-FETs.

This paper presents the design and simulation of static random access memory (SRAM) using two channel spatial wavefunction switched field-effect transistor (SWS-FET), also known as a twin-drain metal oxide semiconductor field effect transistor (MOS-FET). In the SWS-FET, the channel between source and drain has two quantum well layers separated by a high band gap material between them. The gate voltage controls the charge carrier concentration in the quantum well layers and it causes the switching of charge carriers from one channel to other channel of the device. The standard SRAM circuit has six transistors (6T), two p-type MOS-FET and four n-type MOS-FET. By using the SWS-FET, the size and the number of transistors are reduced and all of transistors are n-channel SWS-FET. This paper proposes two different models of the SWS-FET SRAM circuits with three transistors (3T) and four transistors (4T) also addresses the stability of the proposed SWS-FET SRAM circuits by using the N-curve analysis. The proposed models are based on integration between Berkeley Shortchannel IGFET Model (BSIM) and Analog Behavioral Model (ABM), the model is suitable to investigate the gates configuration and transient analysis at circuit level.