Perspective on field‐effect spin‐transistors

Abstract

A new class of spin transistors referred to as spin metal-oxide-semiconductor field-effect transistor (spin MOSFET) is a candidate for the fundamental building block of novel integrated circuts employing spin degrees of freedom. The most attractive feature of the spin MOSFET is spin-related transport phenomena in its output characteristics, i.e., magnetization-configuration-dependent output currents. Furthermore, the spin MOSFET can exhibit excellent performance as a transistor and would have excellent compatibility with present silicon technology. These features make the spin MOSFET attractive for new nonvolatile memory and reconfigurable logic architectures that are inaccessible to ordinary transistor circuits. Transistor performance of the spin MOSFET, such as propagation delay time, switching energy, and stand-by power, is not superior to ordinary MOSFETs on device level. However, the circuit performance would be dramatically improved by introducing spin degrees of freedom into integrated circuits.1 Introduction Progress in integrated electronics is powered by the miniaturization of device (transistor) dimension and the high degree of device integration, since the size shrinkage and large-scale integration of transistors provide improvements in performance of integrated circuits including their reliability and production cost. Recently emerging system-on-chip (SOC) architectures rely on these features of integrated circuits. Metal-oxide-semiconductor field-effect transistors (MOSFETs) and complementary MOS (CMOS) devices (hereafter both are referred to as MOS devices) based on sophisticated Si technology are a fundamental building block for the main stream of integrated circuits, and they play an essential role as a 'technology driver' in integrated electronics. This is, of course, due to the excellent scalability and integration ability of MOS devices. Rapid and continuing progress in the scaled-down technology of MOS devices, that is known as Moore's law, has excluded necessities to introduce new functionality added to MOS devices, such as quantum effects and spin-related phenomena, although these functionalities could be useful to improve the performance of integrated circuits. However, the situation has been changed. Recently, the scaling of the channel length of MOS devices has already reached the physical limit of several nanometers. Therefore, scaling-independent technologies to improve device performance are indispensable. The paradigm shift from the simple device scaling to the introduction of new functionality added to MOS devices is expected as a significantly important path for future integrated electronics technology.The aim of recently emerging spin-electronics (spintronics) research is to manipulate spin degrees of freedom in solid state devices, and provide new concepts for future electronics and photonics employing spin degrees of freedom. One of the most attractive research directions is to control charge transport and spin degrees of freedom in active electronic devices, i.e., spin transist...

Devices and Applications: Spin Transistors and Spin Logic Devices

“…These features of FET-type devices enable them to be applied to high-speed and low-power integrated circuits [1]. The FET type of spin transistor can be classified into two types: the spin-FET [2] (and its modified versions [4][5][6]) and the spin-MOSFET [7] (with several variations [8][9][10]). These spin transistors are comprised of a modulation-doped FET (MODFET) structure or a MOSFET structure in combination with the ferromagnetic source and drain that act as a spin injector and a spin detector, respectively, as shown in Fig.…”

“…The basic structure of spin-MOSFETs [7][8][9][10] is comprised of an MOS capacitor and a ferromagnetic source and drain (S/D). Spin-MOSFETs can be classified by the structure of the ferromagnetic S/D.…”

Characterization of half-metallic L21-phase Co2FeSi full-Heusler alloy thin films formed by rapid thermal annealing

“…In recent years, spin transistors [1][2][3][4][5][6][7] attract considerable attention, since they have interesting transistor behavior with a new degree of freedom in controlling output currents based on spin-related phenomena. This feature makes it possible that spin transistors have useful nonvolatile and reconfigurable functionalities to improve circuit performance beyond present transistors.…”

“…However, high current drive capability and a large on/off current ratio are still important requirements even for spin transistors, as well as present ordinary transistors 7 . In addition, excellent scalability and integration ability are also indispensable to establish very large scale integration.…”

“…In addition, excellent scalability and integration ability are also indispensable to establish very large scale integration. From these points of view, one of the promising spin transistors is recently proposed spin metal-oxide-semiconductor field-effect transistors (spin MOSFETs) [4][5][6][7] . The basic structure of spin MOSFETs consists of a MOS capacitor and ferromagnet contacts for the source and drain, and the device performance depends on the material of the ferromagnetic source/drain.…”