The Application of The Photonic Atom Probe to The Study of Wide Bandgap Semiconductors

The Photonic Atom Probe (PAP) allows for the measurement of Photoluminescence (PL) of a sample tip while it is being analyzed by Laser-Assisted Atom Probe. The femtosecond Laser pulse required for the La-APT measurement also serves to excite the free charge carriers, whose recombination provide the PL signal. As a consequence, it becomes possible to correlate the optical signature of the different parts of a complex structure with the 3D distribution of the contained chemical species [1]. <br/>We present an application of the PAP on III-nitride p-i-n junctions, namely a thick (&gt; 1µm thickness) multi-layer structure containing InGaN quantum wells and a buried tunnel junction [2]. Plasma-assisted molecular beam epitaxy-grown structures, which were used in the study, are characterized by diverse doping concentrations in both p- and n-type regions. The PL spectra can be correlated with the 3D chemical information from APT [3]. The PL signals exhibit indeed a donor-acceptor pair (DAP) emission, whose spectral features can be related to the 3D distribution of the Mg dopants and of the InGaN heterostructures. These results open interesting perspectives for studies of light-emitting defects at the nanoscale.<br/>Besides the interest of this instrument as a microscope [3], the particular conditions in which the optical signatures of localized light emitters are collected open intriguing possibilities for the study of field ion emission under high field and under laser illumination [4]. As an example, the PL spectral shift allows measuring the stress induced by the application of a strong electric field at the tip apex and its propagation through the tip. This has been evidenced both through the study of the stress-induced splitting of the zero-phonon line of the NV⁰ center in diamond [5] and of the quantum well (QW) emission in a ZnO/(Mg,Zn)O system [6], allowing measuring stresss levels ranging from 9 GPa to ~1 GPa.<br/><b>References</b><br/>[1] J. Houard <i>et al.</i>, <i>Review of Scientific Instruments</i>, vol. 91, no. 8, p. 083704, Aug. 2020, doi: 10.1063/5.0012359.<br/>[2] H. Turski <i>et al.</i>, <i>ECS J. Solid State Sci. Technol.</i>, vol. 9, no. 1, p. 015018, Dec. 2019, doi: 10.1149/2.0412001JSS.<br/>[3] E. Di Russo <i>et al.</i>, <i>Nano Lett.</i>, vol. 20, no. 12, pp. 8733–8738, Dec. 2020, doi: 10.1021/acs.nanolett.0c03584.<br/>[4] E. Di Russo and L. Rigutti, <i>MRS Bulletin</i>, vol. 47, no. 7, pp. 727–735, Jul. 2022, doi: 10.1557/s43577-022-00367-6.<br/>[5] L. Rigutti <i>et al.</i>,<i>Nano Lett.</i>, vol. 17, no. 12, pp. 7401–7409, Dec. 2017, doi: 10.1021/acs.nanolett.7b03222.<br/>[6] P. Dalapati <i>et al.</i>, <i>Phys. Rev. Applied</i>, vol. 15, no. 2, p. 024014, Feb. 2021, doi: 10.1103/PhysRevApplied.15.024014.