Design of defect spins in piezoelectric aluminum nitride for solid-state hybrid quantum technologies

Abstract

Spin defects in wide-band gap semiconductors are promising systems for the realization of quantum bits, or qubits, in solid-state environments. To date, defect qubits have only been realized in materials with strong covalent bonds. Here, we introduce a strain-driven scheme to rationally design defect spins in functional ionic crystals, which may operate as potential qubits. In particular, using a combination of state-of-the-art ab-initio calculations based on hybrid density functional and many-body perturbation theory, we predicted that the negatively charged nitrogen vacancy center in piezoelectric aluminum nitride exhibits spin-triplet ground states under realistic uni- and bi-axial strain conditions; such states may be harnessed for the realization of qubits. The strain-driven strategy adopted here can be readily extended to a wide range of point defects in other wide-band gap semiconductors, paving the way to controlling the spin properties of defects in ionic systems for potential spintronic technologies.

Ultrawide‐Bandgap Semiconductors: Research Opportunities and Challenges

“…[271,272] Moreover, rare-earth ions (Nd) doped into AlN may also be a candidate for quantum memories. In this case, it is critical to control inhomogeneous broadening of the dominant rare-earth dopant optical transition, which can be aided by substitutional doping using plasma-assisted MBE, for which it has been shown that the vast majority of Nd dopants (>95%) take the majority site.…”

Designing defect-based qubit candidates in wide-gap binary semiconductors for solid-state quantum technologies

“…For AlN, we used the PBE0 hybrid functional 46 , whose choice for AlN was extensively verified in Ref. 34 (For PBE0, +,-= 0.25, close to the self-consistently determined mixing parameter; 1/ ),+,-= 1/4.16 = 0.24 45 ). Bulk properties of 4H-SiC (see Table 1) and w-AlN (reported in our previous study 34 ) computed with the DDH functionals were found to be in excellent agreement with experimental data 40,47 .…”

“…However, in a previous study on AlN 34 , we showed that the occupied spin-orbitals of V Al O N are in strong resonance with the valence band of the host, which make them unfavorable for spin qubit applications.…”

“…Recent theoretical studies have proposed spin defects in SiC and AlN based on cationic dangling bonds, e.g. Al 3sp 3 states and Si 3sp 3 states [34][35][36] . In a previous work, we showed that the negatively charged N vacancy in w-AlN could have an optically addressable spin-triplet state under a uniaxial or biaxial strain 34 .…”

“…Al 3sp 3 states and Si 3sp 3 states [34][35][36] . In a previous work, we showed that the negatively charged N vacancy in w-AlN could have an optically addressable spin-triplet state under a uniaxial or biaxial strain 34 . Varley et al considered impurity-vacancy complexes in w-AlN based on Group-IV elements including Ge, Sn, Ti, and Zr 36 .…”