Extreme Ultraviolet Radiation Pulsed Atom Probe Tomography of III-Nitride Semiconductor Materials

Laser-pulsed atom probe tomography (LAPT) is a materials characterization technique that has been widely applied in the study and characterization of III-nitride semiconductors. To date, most of these studies have used light sources ranging from the visible to the near-ultraviolet region of the spectrum. In this manuscript, we demonstrate that a recently developed extreme ultraviolet (EUV) radiation pulsed atom probe tomograph can trigger controlled field ion evaporation from III-nitride samples. Experiments indicate that EUV radiation can reliably trigger field ion evaporation from undoped and Mg-doped p-GaN, as well as from Al _x Ga_1-x N and In _x Ga_1-x N alloys using extremely low EUV fluence pulses. While measurements of the chemical composition for GaN using conventional LAPT are known to be highly sensitive to the experimental parameters, the EUV radiation-triggered APT (EUV APT) produces no significant variation in the measured composition over the range of experimentally attainable gallium charge-state ratios. Additionally, the Mg doping concentration values from EUV APT agreed with those obtained by other characterization techniques. The low EUV photon fluence used in these measurements does not appear capable of generating ions via the commonly accepted bulk thermal model, suggesting a different evaporation mechanism.