Electrical Spin Injection into the 2D Electron Gas in AlN/GaN Heterostructures with Ultrathin AlN Tunnel Barrier

Abstract

The spin injection into 2D electron gas (2DEG) in AlN/GaN heterostructures is studied by magneto‐transport measurements. An ultrathin AlN layer at the hetero‐interface acts as a barrier to form high‐quality 2DEG in the triangular quantum well and a tunneling barrier for the spin injection to overcome the conductance mismatch issue. In this study, Hanle signals and inversed Hanle signals are observed, proving that the spin injection is achieved in the 2DEG in the AlN/GaN heterostructure rather than in the interfacial states. The spin‐relaxation time in 2DEG at 8 K is found to be as long as 860 ps, which almost keeps constant with bias and decreases with increasing temperature. The spin‐relaxation process is illustrated as Rashba spin‐orbit coupling dominated D'yakonov Perel’ mechanisms above 8 K. These results show the promising potential of 2DEG in AlN/GaN heterostructures for spin field‐effect transistor applications.

Half‐Metallic Heusler Alloy/GaN Heterostructure for Semiconductor Spintronics Devices

“…Here, we can expect little effect of the formed layer on the spin injection and detection because the ultrathin Al‐doped GaN (or AlGaN) layer becomes an appropriate tunnel barrier layer with a low contact resistance. [ 29 ]…”

“…Here, we can expect little effect of the formed layer on the spin injection and detection because the ultrathin Al-doped GaN (or AlGaN) layer becomes an appropriate tunnel barrier layer with a low contact resistance. [29] Figure 4 shows the magnetic-field dependence of the magnetization (M-H curve) for an epitaxial CFAS/GaN heterostructure at room temperature (300 K). The saturation magnetic moment (M S ) is estimated to be ≈4.7 𝜇 B /f.u., which is equivalent to the M S values for the CFAS films grown on a Si(111) or Ge(111) substrate in our previous studies.…”

“…[23][24][25][26][27][28][29] However, almost all of the previous related studies have used an insulating tunnel barrier such as MgO and AlN for electrical spin injection into GaN to solve the spin resistance mismatch problem, [30][31][32] resulting in high-resistance contacts with a resistance-area product (RA) higher than several MΩμm 2 . [20,21,29] If such high-resistance contacts were utilized, they would limit the future use of GaN in applications such as medical spin LEDs, [33] and spin-polarized lasers (spin lasers) for ultrafast switches, high-performance reconfigurable interconnects, and secure communications on chips. [34][35][36][37] Although a spin laser was experimentally demonstrated in a GaN-nanorod array coupled with Fe 2 O 3 nanoparticles at room temperature in 2014, [38] spin injection was performed by optical pumping with circularly polarized light, giving rise to an obstruction for onchip battery-operated devices.…”

Spintronic Terahertz Emission in Ultrawide Bandgap Semiconductor/Ferromagnet Heterostructures

“…[23] This STC conversion may be due either to the bulk Rashba or inverse spin hall effect (ISHE), or the interfacial Rashba effect, which manifests in systems with broken inversion symmetry, such as two-dimensional electron gases (2DEGs). [15,24] In all-metallic systems, a nonmagnetic heavy metal such as Pt is often used to generate large charge currents. However, in most common semiconductors, the spin Hall angle θ SH is relatively small.…”

Simulation study of a novel AlGaN/GaN L‐FER with ultralow turn‐on voltage and low reverse leakage

“…Currently, GaN-based semiconductors have attracted a lot of interest in many fields, likely power electronics (due to the wide bandgap), optoelectronics (due to the high luminous efficiency), and spintronics (due to an electric-field controllable spin-orbit coupling and potential device applications at room temperature) [1][2][3][4][5]. In power electronics, AlGaN/GaN high electron mobility transistors (HEMTs) are the most studied GaN-based power transistors, owing to their high breakdown voltage (BV), low specific on-resistance (R on,sp ), and high-velocity two-dimensional electron gases (2DEG) [6].…”