Thermal Desorption of Helium from Defected Silicon

Abstract

The thermal desorption spectroscopy measurements of He implanted silicon samples are reported. The He implantation energy was 90 keV (at 45• tilt) while the fluence was 10 16 cm −2 . Additionally, the influence of Si pre-implantation (fluences in the range 10 14 −10 16 cm −2 , E = 260 keV) was under investigation. The He releases from both interstitials/vacancies (β peak) and cavities (α peak or rather band consisting probably of at least two peaks) were observed. The α peak disappears for the pre-implantation fluences larger than 10 15 cm −2 , while β peak becomes broader and shifts toward higher temperatures. The thermal desorption spectra were collected using heating ramp rates in the range 0.3-0.7 K/s. Desorption activation energy of the β peak for different pre-implantation fluences was found using the Redhead analysis of the β peak shift. It varies from 0.97 eV for the sample that was not pre-implanted up to 1.3 eV for the sample pre-implanted with the fluence 10 16 cm −2 .

Thermal Desorption of He Implanted into Ge

“…The calculations were performed using the SRIM software [31]. The projected implantation ranges were 410 nm (80 keV) and 490 nm (100 keV), being comparable to that obtained for tilted (45 • ) He implantation to Si [30] due to the differences in target density. Also the maximum dopant concentrations are comparable.…”

“…The thermal desorption spectrometer used during the measurements was described in details in our previous papers [24][25][26]30]. Some brief description is given for the sake of completeness.…”

“…This paper presents the results of TDS measurements of He implanted (100 and 80 keV) to the germanium samples with smaller fluences (1 × 10 16 cm −2 ) than in [30], still large enough to lead to bubble formation in the case of Si. The TDS spectra collected for both implantation energies using the heating ramp rates in the range 0.45 K/s up to 1.5 K/s are presented and discussed.…”

Thermal Desorption of Krypton Implanted into Silicon

“…5 (E = 200 keV). A sudden Kr release is observed in the temperature range 1050-1400 K. It should be noted that it is at least 100 K higher than that observed for Ar implanted with E = 115 keV [24], and much higher than release temperatures for much more mobile He (700-800 K) [25]. Such difference could be explained, for example by the above mentioned fact that Kr has larger atomic radius (≈ 2.0 Å) compared to He (1.2 Å) [20].…”

“…A construction and principle of operation of the TDS spectrometer was described in detail in our previous papers [24,25]. However, a brief overview is given here for completeness sake.…”