Large current modulation and tunneling magnetoresistance change by a side-gate electric field in a GaMnAs-based vertical spin metal-oxide-semiconductor field-effect transistor

Toshiki Kanaki,Tomohiro Koyama,Daichi Chiba,Shinobu Ohya,Masaaki Tanaka,Hiroki Yamasaki

doi:10.1038/s41598-018-24958-z

Abstract

A vertical spin metal-oxide-semiconductor field-effect transistor (spin MOSFET) is a promising low-power device for the post scaling era. Here, using a ferromagnetic-semiconductor GaMnAs-based vertical spin MOSFET with a GaAs channel layer, we demonstrate a large drain-source current IDS modulation by a gate-source voltage VGS with a modulation ratio up to 130%, which is the largest value that has ever been reported for vertical spin field-effect transistors thus far. We find that the electric field effect on indirect tunneling via defect states in the GaAs channel layer is responsible for the large IDS modulation. This device shows a tunneling magnetoresistance (TMR) ratio up to ~7%, which is larger than that of the planar-type spin MOSFETs, indicating that IDS can be controlled by the magnetization configuration. Furthermore, we find that the TMR ratio can be modulated by VGS. This result mainly originates from the electric field modulation of the magnetic anisotropy of the GaMnAs ferromagnetic electrodes as well as the potential modulation of the nonmagnetic semiconductor GaAs channel layer. Our findings provide important progress towards high-performance vertical spin MOSFETs.

Highlights

IntroductionAfter the device was bonded with Au wires and indium solder, we measured the spin-dependent transport properties of our spin MOSFET with varying VGS and H at 3.8 K
We obtained a large current modulation ratio up to 130%, which is the largest value that has ever been reported far for the vertical spin FETs16,17
By comparing the experimental data with the calculated results, we concluded that this large IDS modulation does not originate from the modulation of direct tunneling between the source and the drain but from the modulation of the indirect tunneling current via defect states in the intermediate GaAs layer

Summary

Introduction

After the device was bonded with Au wires and indium solder, we measured the spin-dependent transport properties of our spin MOSFET with varying VGS and H at 3.8 K. The experimental data of our vertical spin MOSFET are collected from 20 mesas that are connected by the drain electrode in the comb-shaped chip. To measure the θ dependence of TMR, we applied a strong magnetic field of 1 T in the opposite direction of θ to align the magnetization directions and we decreased H to zero. We started to measure RDS while increasing H from zero in the direction of θ. The measurements were performed at every 10° step of θ. We note that our experimental data are reproducibl

Methods

Results

Conclusion