A photonic atom probe coupling 3D atomic scale analysis with in situ photoluminescence spectroscopy

Abstract

Laser enhanced field evaporation of surface atoms in Laser-assisted Atom Probe Tomography (La-APT) can simultaneously excite phtotoluminescence in semiconductor or insulating specimens. An atom probe equipped with appropriate focalization and collection optics has been coupled with an in-situ micro-Photoluminescence (µPL) bench that can be operated during APT analysis. The Photonic Atom Probe instrument we have developped operates at frequencies up to 500 kHz and is controlled by 150 fs laser pulses tunable in energy in a large spectral range (spanning from deep UV to near IR). Micro-PL spectroscopy is performed using a 320 mm focal length spectrometer equipped with a CCD camera for time-integrated and with a streak camera for time-resolved acquisitions. An exemple of application of this instrument on a multi-quantum well oxide heterostructure sample illustrates the potential of this new generation of tomographic atom probe.

In Situ Spectroscopic Study of the Optomechanical Properties of Evaporating Field Ion Emitters

“…The sawtooth profile is visible when the observation is performed along the polar [0001] direction (c-direction, z axis for the strain/stress tensors) [22]. The [11][12][13][14][15][16][17][18][19][20] adirection corresponds to the y axis for the strain/stress tensors. The orientation of the crystal is also visualized in Fig.…”

“…1, while the technical details of the instrument used in this study are discussed in Ref. [15]. The nanometric needle-shaped specimen is polarized with a voltage VDC = 3 -16 kV, leading to an apex electric field of a few tens of V/nm [23,24].…”

“…In this contribution, we report about an original way to access to the stress state of nanoscale field ion emitters through the use of a photonic atom probe (PAP) [15,16], whose principles are schematically illustrated in fig. 1.…”

Super-resolution Optical Spectroscopy of Nanoscale Emitters within a Photonic Atom Probe

“…5−7 As an evolution of laserassisted-APT 8 in which ion evaporation is controlled by laser pulses, a 3D photonic atom probe (PAP) features in situ and operando PL coupled with APT analysis. 9 During the analysis, the series of collected spectra evolves smoothly due to the slow and controlled evaporation of the atomic monolayers constituting the specimen. It becomes thus possible to discriminate the spectral features of distinct spatial regions lying at distances much lower than the diffraction limit of the exciting laser (i.e., performing super-resolution spectroscopy) and to simultaneously correlate this information with the 3D structure of nanoscale light emitters in terms of chemical composition, interface definition, and morphology.…”

“…The instrument is able to collect and analyze in situ and in real time the photoluminescence that laser pulses excite simultaneously with surface atom evaporation. 9 The collection of the PL signal during APT translates into a series of spectra such as that reported in Figure 1b. The optical information can then be retrieved from the analysis of single or multiple spectra.…”