Strong Zero-Phonon Transition from Point Defect-Stacking Fault Complexes in Silicon Carbide Nanowires

Abstract

Crystallographic defects such as vacancies and stacking faults engineer electronic band structure at the atomic level and create zero-and two-dimensional quantum structures in crystals. The combination of these point and planar defects can generate a new type of defect complex system. Here, we investigate silicon carbide nanowires that host point defects near stacking faults. These point−planar defect complexes in the nanowire exhibit outstanding optical properties of high-brightness single photons (>360 kcounts/s), a fast recombination time (<1 ns), and a high Debye−Waller factor (>50%). These distinct optical properties of coupled point-planar defects lead to an unusually strong zero-phonon transition, essential for achieving highly efficient quantum interactions between multiple qubits. Our findings can be extended to other defects in various materials and therefore offer a new perspective for engineering defect qubits.

Thermal Conductivity of 3C/4H-SiC Nanowires by Molecular Dynamics Simulation

“…Zhijiang Wang et al fabricated 3C-SiC nanowires with different states of stacking faults by varying the heating temperature [15]. Je-Hyung Kim et al found that CVD-grown 3C-SiC nanowires may include hexagonal inclusions that are a few nanometers thick (4H-or 6H-SiC) by stacking faults [16]. Apart from the stacking faults that may occur during the preparation process, phase separation of solid-state binary compounds (e.g., 4H-SiC) induced by laser-material interaction has been observed [17][18][19].…”

Designing silicon carbide heterostructures for quantum information science: challenges and opportunities

“…The presence of such imperfections in commercial materials has, however, revealed that they can be exploited to obtain emergent properties of profound use for future QIS applications. These include the enhancement of ZPL emission [56] and the stabilization of ZPLs at different photon energies than expected in a pure material [24]. The challenge to engineer SFs and heteropolytypic inclusions in a precise manner so as to tailor material and color center properties on demand necessitates molecular-scale insights into the synthesis process.…”

“…A SL of alternating SiC polytypes, as shown in figure 4(d) for a 4H/6H structure, represents a multi-QW system that can be used to amplify confinement effects. The build up of precisely engineered SFs inherent to each polytype switch within the SL, combined with thin layering, may further enhance ZPL emission that has been demonstrated in low-dimensional SiC systems with known but unintentional SFs [56]. In addition, point defect charge state stability [73,212,213] could be enhanced in SiC SLs via confinement of free carrier recombination.…”

“…Conversely, color centers may be synthesized within an inclusion layer during CVD synthesis. The QW-stabilization of point defects inherent in such a structure (figures 1(b)-(d)) [24,46,56,57] could inhibit color center diffusion out of the inclusion layer and into the surrounding polytype layers. This scheme relies on having detailed knowledge of CVD process variables that provide polytype stability while simultaneously allowing for C/Si tunability to generate intrinsic color centers (e.g., monovacancies) during synthesis of the inclusion layer through site-competition epitaxy [69].…”

“…Understanding the formation of structural defects promises to provide not only superior monopolytypic materials but also new avenues toward the synthesis of high quality heteropolytypic multilayer structures that could serve as a basis for future QIS materials. QWs created by SFs and polytype inclusions in SiC have been suggested to enhance zero phonon line (ZPL) emission from optically active defects [56], shift ZPLs [57], or generate new ZPLs [24,58,59]. Polytypic heterojunctions can host two-dimensional electron gases (2DEGs) [60][61][62] with potentially superior properties (e.g., sheet carrier densities) compared to those of more standard 2DEG materials, such as AlGaN/GaN [63].…”