Hydrogen implanted silicon has been shown to cleave upon annealing, thus facilitating the transfer of thin silicon slices to other substrates, a process known as “ion-cut.” In our experiments 〈100〉 silicon wafers were implanted with 40 keV protons to a variety of ion doses ranging from 1×1016 to 1×1017 cm−2 and subsequently annealed at 600 °C. The samples were studied before and after annealing by a combination of Rutherford backscattering spectroscopy in channeling mode, elastic recoil detection analysis, atomic force microscopy, and electron microscopy. Mechanical stresses in the material, caused by proton irradiation, were determined by measuring changes in curvature of the silicon samples utilizing a laser scanning setup. For H doses of ⩾5×1016 cm−2 ion cutting in the form of “popping off” discrete blisters was obtained. Our analyses of the cleavage mechanisms had shown that the ion-cut location in silicon is largely controlled by the lattice damage that is generated by the H implantation process. At ...

Physical mechanisms behind the ion-cut in hydrogen implanted silicon

The physical mechanisms of hydrogen induced silicon surface layer exfoliation were investigated using the combination of ion beam analysis, secondary ion mass spectroscopy (SIMS), scanning electron microscopy (SEM), and cross section transmission electron microscopy (XTEM). A 〈100〉 oriented silicon wafer was implanted with 175 keV protons to a dose of 5×1016 cm−2. The implanted wafer was bonded to a silicon oxide capped 〈100〉 silicon wafer and then heated to an elevated temperature of 600 °C to produce exfoliation. The hydrogen-implanted sample was analyzed in the as-implanted state as well as after the cleavage of the silicon wafer. The depth distribution of the implantation damage was monitored by Rutherford backscattering spectrometry (RBS) in channeling condition and XTEM imaging. Elastic recoil detection analysis and SIMS was performed to examine the hydrogen depth distribution. Cross section SEM and RBS channeling was used to measure the thickness of the exfoliated layer after cleavage. A comparison...

Investigation of the cut location in hydrogen implantation induced silicon surface layer exfoliation

Measurements of the electronic stopping power of He2+ ions along the 〈100〉 direction in Si crystal with energies ranging between 200 keV and 4.5 MeV are presented. The Rutherford backscattering technique has been used with SIMOX samples consisting of a Si single-crystal layer on top of a buried layer of 500 nm SiO2 built into a Si 〈100〉 wafer.

Electronic stopping power of 〈100〉 axial-channelled He ions in Si crystals

We have simultaneously measured angular distributions and electronic energy loss of helium ions and protons directly transmitted through self-supporting, single-crystalline silicon foils. We have compared the energy loss along channeled and random trajectories for incident ion energies between 50 and 200 keV. For all studied cases the energy loss in channeling geometry is found lower than in random geometry. In the case of protons, this difference increases with initial ion energy. This behavior can be explained by the increasing contribution of excitations of core electrons, which are more likely to happen at small impact parameters accessible only in random geometry. For helium ions we observe a reverse trend---a decrease of the difference between channeled and random energy loss for increasing ion energy. Because of the inefficiency of core-electron excitations even at small impact parameters at such low energies, another mechanism has to be the cause for the observed difference. We provide evidence that the observation originates from reionization events induced by close collisions of helium ions occurring only along random trajectories.

https://link.aps.org/pdf/10.1103/PhysRevLett.124.096601

Disparate Energy Scaling of Trajectory-Dependent Electronic Excitations for Slow Protons and He Ions.

A review is given on the application of the coupled-channel method for the calculation of the electronic energy loss of ions as well as ionization in matter. This first principle calculation, based on the solution of the time-dependent Schrodinger equation, has been applied to evaluate the impact parameter and angular dependence of the electronic and nuclear energy losses of ions as well as the ionization due to high-power short laser pulses. The results are compared to experimental data as well as to other current theoretical models.

Ionization and Energy Loss Beyond Perturbation Theory

Experimental results on the angular dependence of energy loss for 2 MeV channeled He + ions along the Si〈100〉 axis by use of transmission channeling are presented. The measured angular width of this dependence is significantly smaller than the corresponding experimental value for the nuclear encounter probability. A modified two component assumption for the energy loss gives an excellent agreement to the experimental results. Based on this two component assumption, and separating the contributions from valence electrons and core electrons, a simple empirical expression for the energy loss channeled ions is proposed. A method is developed to extract the average L shell electron density distribution in the channel from the measured angular dependence. The peak of the distribution is at 0.18 A.

The angular dependence of energy loss of channeled 2 MeV helium ions along Si 〈100〉 axis

Ion-beam mixing to create thermoelectric properties in alloys

Ions of 120 keV Xe + , 100 keV Ne + and 120 keV H + 2 have been implanted to various doses in 2.6 μm epitaxial layers of yttrium iron garnet (Y 3 Fe 5 O 4 ) grown on 〈111〉 single crystal gadolinium gallium garnet. Rutherford backscattering and resonant 16 O(α, α) 16 O scattering of channeled 3.07 MeV 4 He + ions have been measured to study crystal distortions induced during room temperature implantation. Strain close to the surface was obtained from the angle change between 〈110〉 and 〈100〉 axes as measured by channeling in implanted and unimplanted parts of the crystal. The damage profile was obtained directly from the energy spectrum of backscattered particles. A simple method to evaluate strain profiles from the measured RBS (Rutherford Backscattering) spectra has been used.

Comparison of strain and damage profiles induced by implantation of Xe+, Ne+ and H2+ ions in yttrium iron garnet

Using the channeling technique, the co-operative Jahn-Teller effect in nickel chromite single crystals has been studied by helium ion backscattering and the resonant nuclear scattering of O16(α,α)O16 at Eα = 3.056 MeV. The results have shown that the chan dips for Ni + Cr and O atoms around 〈110〉, 〈111〉 and 〈111〉 axes become shallow at temperatures below the dynamic to static Jahn-Teller transition, which has been attributed to extra dechanneling due to the domain effect and explained by the (110) twin model. Also there is some indication that the Ni or Cr atoms (or both) are laterally displaced from the 〈111〉 or 〈111〉 axis at temperatures lower than the transition temperature. This differs from the usual expectation for the co-operative Jahn-Teller effect.

Channeling study of the co-operative Jahn-Teller effect in nickel chromite single crystal by backscattering and resonant nuclear scattering of helium ions

H.-S. Jin

Papers

The angular dependence of energy loss of channeled 2 MeV helium ions along Si 〈100〉 axis

Ion-beam mixing to create thermoelectric properties in alloys

Comparison of strain and damage profiles induced by implantation of Xe+, Ne+ and H2+ ions in yttrium iron garnet

Channeling study of the co-operative Jahn-Teller effect in nickel chromite single crystal by backscattering and resonant nuclear scattering of helium ions