Two-dimensional spin systems in PECVD-grown diamond with tunable density and long coherence for enhanced quantum sensing and simulation

TL;DR

This paper demonstrates a refined method to create dense, two-dimensional nitrogen and NV spin layers in diamond with tunable density, depth confinement down to 1.6 nm, and long coherence times, advancing quantum sensing and simulation capabilities.

Contribution

It introduces a delta-doping PECVD growth technique to engineer dense 2D spin layers in diamond with controlled properties and detailed characterization of their density, depth, and coherence.

Findings

P1 densities of 5-10 ppm·nm achieved

NV densities of 1-3.5 ppm·nm tunable via irradiation

Depth confinement of spin layers down to 1.6 nm

Abstract

Systems of spins engineered with tunable density and reduced dimensionality enable a number of advancements in quantum sensing and simulation. Defects in diamond, such as nitrogen-vacancy (NV) centers and substitutional nitrogen (P1 centers), are particularly promising solid-state platforms to explore. However, the ability to controllably create coherent, two-dimensional spin systems and characterize their properties, such as density, depth confinement, and coherence is an outstanding materials challenge. We present a refined approach to engineer dense ($\gtrsim$1 ppm$\cdot$nm), 2D nitrogen and NV layers in diamond using delta-doping during plasma-enhanced chemical vapor deposition (PECVD) epitaxial growth. We employ both traditional materials techniques, e.g. secondary ion mass spectrometry (SIMS), alongside NV spin decoherence-based measurements to characterize the density and dimensionality of the P1 and NV layers. We find P1 densities of 5-10 ppm$\cdot$nm, NV densities between 1 and 3.5 ppm$\cdot$nm tuned via electron irradiation dosage, and depth confinement of the spin layer down to 1.6 nm. We also observe high (up to 0.74) ratios of P1 to NV centers and reproducibly long NV coherence times, dominated by dipolar interactions with the engineered P1 and NV spin baths.