Implanted hydrogen

K. L. Wilson, et al.. Trapping, Detrapping and Release of Implanted Hydrogen Isotopes, 1991, IAEA. 

This brings us to the subject of standards. In this connection a standard is simply a sample with a known hydrogen content that is used for convenience to calibrate the overall counting efficiency of a particular setup, i.e., to determine the factor AfICalibration standards must be stable under irradiation. While plastic foils of known composition can be used if precautions are taken (Rudolph et al., 1986), their intrinsic instability makes them unsuitable. The standard used by most groups is hydrogen-implanted silicon, which has the advantages that it is easily prepared, the implanted dose can be measured to 5%, and the amount of implanted hydrogen is stable at room temperature and under MeV 15N irradiation, as discussed later. 

The ion-beam analysis techniques described in preceding sections have been applied in many investigations of hydrogen in semiconductors. In this section we will mention studies in two areas where ion-beam analysis of H has made a significant contribution these are the thermal release and redistribution of implanted hydrogen and the absolute measurement of IR absorption cross sections in a-Si H. In addition, we will mention a developing field, the study of hydrogen in interfaces. 

The conclusion to be drawn from these studies as far as the suitability of different ion-implanted hydrogen standards is concerned is that pre-amorphized silicon is the best target material, though crystalline silicon is an acceptable alternative if room temperature is never exceeded. 

Applications of Lattice Location a. The Site Occupied by Implanted Hydrogen... 

The close correspondence between the properties of Mu in Si as determined by /u,SR and pLCR and those for the AA9 center produced by implanting hydrogen in silicon shows that Mu in silicon and the AA9 center are isostructural and in fact almost identical. They are neutral isolated bond-centered interstitials. Numerous theoretical studies support this conclusion. The observation of such similar centers for muonium and hydrogen supports the generalization that hydrogen analogs of many of the muonium centers exist. Of course, this assumes that the effects of the larger zero-point vibration of the muon relative to the proton do not make a major contribution to structural differences. The p-SR experiments, reinforced by theory, demonstrate that another structure also exists for muonium in silicon, called normal muonium or Mu. This structure is metastable and almost certainly is isolated neutral muonium at a tetrahedral interstitial site. 

The smart cut, a recently developed technique at Leti, Grenoble, France [45], allows even better control of the top layer s thickness while reclaiming the top silicon wafer used in BESOI wafers. It makes use of implanted hydrogen at the separation depth. The smart cut technique is used in Unibond wafers. 

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