Effect of Heavy Ion Implantation and Laser Annealing on the Structural Properties of Germanium

Abstract

A yield deficit in RBS spectra is observed for Ge and Sb implants, a less pronounced but observable effect is found for In implant, and no change in BBS spectra is detected for Kr implant into Ge. The effect is dose dependent, after reaching a critical dose, the yield deficit appears. This critical dose is 3 × 1015 atom/cm2 for Ge and 2 × 1015 atom/cm2 for Sb implantation and with increasing dose the yield deficit becomes more and more pronounced. This is similar to earlier findings. In all cases, except for the noble gas (Kr, Xe) implants, the color of the implanted specimen turns to black. At the same time, SBM investigations show a peculiar surface morphology. Xe–Sb double implants are also investigated. Implanting first the noble gas (Xe) and then Sb, the effect is not observed. Laser annealing of In implanted Ge with Q‐switched ruby laser (25 ns, 0.51 Jcm−2) results in a fairly good recrystallization and segregation of the indium to the surface. The peculiar surface morphology together with the color change disappears due to pulsed laser annealing.

Disorder and cavity evolution in single-crystalline Ge during implantation of Sb ions monitored in-situ by spectroscopic ellipsometry

“…The reason for the differences can be explained considering the dissimilar conditions for the lower energy Sb + and the high energy I + irradiation. The electronic energy deposition in "hot" collision cascades which are associated with temperature increase and local target melting [40] is about 4 times higher for the I + irradiation, as predicted by SRIM, and therefore the probability to directly form larger amorphous clusters via local melting and fast cooling [40] is higher compared to our case of Sb + implantation into Ge. On the other hand, the higher local temperature may be accompanied by different in-situ defect formation, annealing, cluster formation and diffusion kinetics of defects for 3 MeV I + compared to 200 keV Sb + .…”

“…S5 in the Supplementary Material). When implanting heavy elements in Ge (Ge ions or heavier species), void formation occurs, and above a certain fluence a peculiar cellular structure develops [8,16,17,19,[39][40][41][42][43][44]. Similar effects were observed in Si [45], CdTe [46] and SiC [47].…”

“…A much simpler assumption is to take into account that the ions impinging at random positions of the surface satisfy the Poisson statistics, i.e., the probability that the next ion finds a non-damaged position is proportional to the area of the surface that has not yet been amorphized [62]. It has been shown that an individual ion track generated by a bombarding ion leads to rapid temperature increase and melting of the track zone in the target material [40]. This process results in the formation of a residual circular amorphous zone with its radius on the nanometer scale around the ion trajectory due to fast cooling and quenching of the displaced target atoms in the collision cascade zone.…”

“…The radius of such residual amorphous tracks depends mainly on the energetics of the collision cascade, i.e., the mass and energy of the implanted ion and the properties of the target material. Therefore, a characteristic ion track radius (R T ) can be anticipated for each implantation process with given ion mass, ion energy, and target material [40]. Fig.…”