Defect engineering of silicon with ion pulses from laser acceleration

Abstract

Defect engineering is foundational to classical electronic device development and for emerging quantum devices. Here, we report on defect engineering of silicon with ion pulses from a laser accelerator in the laser intensity range of 1019 W cm−2 and ion flux levels of up to 1022 ions cm−2 s−1, about five orders of magnitude higher than conventional ion implanters. Low energy ions from plasma expansion of the laser-foil target are implanted near the surface and then diffuse into silicon samples locally pre-heated by high energy ions from the same laser-ion pulse. Silicon crystals exfoliate in the areas of highest energy deposition. Color centers, predominantly W and G-centers, form directly in response to ion pulses without a subsequent annealing step. We find that the linewidth of G-centers increases with high ion flux faster than the linewidth of W-centers, consistent with density functional theory calculations of their electronic structure. Intense ion pulses from a laser-accelerator drive materials far from equilibrium and enable direct local defect engineering and high flux doping of semiconductors.

Quantum Emitter Formation Dynamics and Probing of Radiation-Induced Atomic Disorder in Silicon

“…Here, we explore radiation-induced G-center formation dynamics in silicon wafers under various protonirradiation conditions: (1) by using the induction linear accelerator that is part of the Neutralized Drift Compression Experiment (NDCX-II) at the Lawrence Berkeley National Laboratory, which delivers an approximately 1-MeV intense nanosecond-pulsed proton beam and allows us access to transient radiation effects on defect dynamics far from equilibrium at the nanosecond time scale [10,30]; and (2) by using 1-MeV continuous-wave (cw) proton irradiation with orders-of-magnitude-lower dose rates performed in the Centro Nacional de Aceleradores, Seville, Spain [31]. Our present study complements earlier siliconirradiation studies with pulsed-proton and ion pulses from laser accelerators and higher damage rates [32]. We compare the G-center optical properties characterized by time-resolved photoluminescence (PL) and reveal the dose-rate effect on color-center formation efficiency and optical line width.…”

“…In detail, only the nonradiative defects that cause the strain-field fluctuation within the spread of the localized state of the G centers contribute to the linewidth broadening. The spread of localized-defect states in silicon is typically about a few nanometers [32,42,44]. On the other hand, any nonradiative defects with a distance to G centers within the carrier diffusion length (micrometer scale [45]) will affect the G-center PL decay and quantum efficiency.…”

Programmable quantum emitter formation in silicon

“…G, T, H, C i centers are part of a family of carbon-related quantum emitters in silicon 38 . The G center in Si is among the most common defect centers and can be formed readily by C ion implantation followed by rapid thermal annealing under inert gas ambiance, as well as by proton irradiation, and laser-ion doping 39 – 41 . The formation of the G center follows a widely accepted two-step process.…”

Solid-State Color Centers for Single-Photon Generation

“…Particular care must be taken in how different thermal treatment durations used to supply the thermal budget can affect the evolution and stabilization of the G center with respect to competing defective complexes. Proof of this lies in the lower temperature reported for the annealing out of the W (~400 • C [111,131,132] and G center (~250 • C [101]) following conventional rapid thermal annealing and compared to the peak temperature estimated in ns-pulsed ion implantation [133]. Non-equilibrium processes with µs-long high-power laser exposure combined with surface functionalization based on organic molecules have also promoted the incorporation of carbon atoms above the solubility limit, thus creating a highly dense ensemble of G centers [105].…”

“…For instance, strain engineering has provided a useful method to tune the splitting of the G center ZPL in doublets or quadlets up to 18 meV [138], and particular attention has been paid to avoiding the introduction of unwanted radiation-related defects while developing nanopatterning processes to integrate these sources in photonic platforms [139]. In addition, a 30-fold enhancement of the photoluminescence coming from single G emitters and an 8-fold Purcell enhancement of their emission rate has been recently achieved in an all-silicon cavity [133]. Cryogenic temperatures do not necessarily represent a practical limitation in the photonic circuit integration, where low-temperature conditions are already required; for instance, for the integration of superconducting nanowire single-photon detectors.…”