Damage studies of MeV Sb-implanted Si(100) by channeling and Raman spectroscopy

Abstract

The effect of as-implanted damage on the microstructure of threading dislocations in MeV implanted siliconThe radiation damage induced in Si͑100͒ due to 1.5 MeV Sb ions has been studied as a function of fluence using the Rutherford backscattering/channeling ͑RBS/C͒ technique and Raman spectroscopy. The damage profiles have been extracted from the RBS/C spectra and the results compared with SRIM'97 code calculations. For a fluence of 1ϫ10 14 ions/cm 2 , though the position of the damage profile is in agreement with the defect profile calculated using SRIM code, theory overestimates the damage in the surface region, suggesting dynamic self-beam annealing. The total amount of damage obtained as a function of implant dose exhibits two behaviors; a small net damage and a slow rate of damage accumulation for low fluences with a crossover to faster rates beyond a dose of 1ϫ10 13 ions/cm 2 . At this dose, a defected-amorphized zone of a critical size can form, which may easily enlarge by further accumulation of defects at higher fluences. The total damage has been compared with the results from Raman scattering and it is observed that the net damage as detected by Raman is slightly higher at the fluences where crystalline and amorphous zones coexist. The crystalline-to-amorphous ͑c/a͒ transition in Si as a function of fluence has been investigated by RBS/C and Raman scattering. The study demonstrates that Raman scattering is more effective in probing the small concentrations of defects produced during the early stages of c/a transition.

Shape transition of nanostructures created on Si(100) surfaces after MeV implantation

“…Our earlier RBS/C and Raman scattering results [9,11] show that Si lattice disorder also displays 3 similar behaviours as a function of ion fluence. Initially a low lattice damage, due to simple defects, is seen upto the fluence of 1 × 10 13 ions/cm 2 .…”

“…The shape transition of nanostructures, from being elliptical at lower fluence to deformed circular at 5×10 14 ions/cm 2 , may be caused by the increase in the density of the electronic excitations. Our earlier studies [9,11] show that the amorphization of Si-surface at this stage also leads to stress relaxations on the ion implanted surface.…”

“…These nanostructures inflate in size with increasing fluence. The size inflation may also be related to the increased disorder [9,11] in the Si lattice. The shape transition of nanostructures, from being elliptical at lower fluence to deformed circular at 5×10 14 ions/cm 2 , may be caused by the increase in the density of the electronic excitations.…”

Nano-scale depth-varying recrystallization of oblique Ar+ sputtered Si(111) layers

“…This decrease is found to be 42% of the total damage at oblique incidence of 30°, resulting in recrystallized layer of thickness 32 nm. Surprisingly, complete recrystallization could not be attained upon thermal annealing at 1,073 K. This can be attributed to the agglomeration of isolated point defects into extended defect zones 11,18 , thereby, making difficulty in annealing even at a temperature of 1,073 K.…”

“…In addition to these beneficial features, this non-equilibrium method disorders the equilibrium crystalline structure of the single crystal material by inducing amorphization as well as damage in the lattice 5 – 7 , 9 , 10 . The extent and nature of these ion beam induced imperfections in the lattice limits the performance and reliability of semiconductor devices and circuits 1 , 6 , 11 . This, in turn, necessitates the recovery of crystalline order of the lattice 5 , 9 , 10 , 12 , 13 .…”