Local modes of vibration

FREQUENCIES OF THE HYDROGEN LOCAL MODES OF VIBRATION AT 5 K OBSERVED IN BULK III-V MATERIALS. WHEN OBSERVED, THE CORRELATION WITH A DOPANT IS INDICATED. 

FREQUENCIES OF THE LOCAL MODES OF VIBRATION OBSERVED AFTER PROTON OR DEUTERON IMPLANTATION OF III-V COMPOUNDS. THE MEASUREMENT TEMPERATURE AND THE TYPE OF ATOM TO WHICH H (OR d) IS BONDED ARE INDICATED. 

The observation of most of the lines reported in Table IV is not correlated with the doping of the material. At least two possibilities exist to explain them they are either due to the neutralization by hydrogen of accidental impurities or to the local mode of vibration of hydrogen at a lattice defect site. 

Evidence exists that some of the lines correspond to the second type of complexes. Figure 20 shows with the same wavenumber scale the absorption in bulk as grown InP material and in proton and deuteron implanted material. It is clear that the two local modes of vibration are observed at exactly the same energies (2202.4 cm-1 and 2315.6 cm-1) in as grown and... 

The second type of absorption concerns local modes of vibration of defects or complexes involving hydrogen or deuterium. 

Because of the lattice damage, the absorptions due to the local modes of vibration are usually broader in implanted materials than, for instance, in plasma diffused samples. For proton energies around 1 MeV, the line-widths are in the range 5-100 cm-1 (as compared with 0.1-5 cm-1 for plasma hydrogenation). 

Table V summarizes all the sharp absorptions due to local modes of vibration in proton and deuteron implanted GaP, GaAs and InP. It has to be noted that the results depend upon the reports. For instance, for GaP implanted with protons, Newman and Woodhead (1980) observed only one line at 1849 cm-1 whereas Sobotta et al. (1981) observed only one line at 2204 cm-1. These differences probably come from the differences in implantation conditions. However, unfortunately, these conditions are not always well described in the literature the ion energy and dose are usually given, but the ion current is specified only by Tatarkiewicz et al. (1987, 1988). This parameter is of importance as it contributes to control local temperature and therefore the defect creation and the binding of hydrogen to the lattice. 

The thermal stability of the centers responsible for the local modes of vibration has been investigated. In GaP, Sobotta etal. (1981) observed that annealing of the implanted samples at 240°C for one hour leads to a narrowing of the 2204 cm 1 absorption line. This is due to the annealing of the radiation damage. Annealing at 400°C for one hour decreases drasti-... 

Fig. 22. Local modes of vibration of a deuteron-implanted InP crystal (fluence 5.1017 cm-2) immediately after implantation (full line) and after annealing for 30 min. at 200°C (—) 300°C (- -) and 400°C (—). Reprinted with permission from V. Riede et al., Solid State Commun. 65, 1063, 1988. Pergamon Press PLC.

FREQUENCIES OF THE LOCAL MODES OF VIBRATION AT 5 K OF HYDROGEN SATURATING A DANGLING BOND IN A VACANCY IN VARIOUS SEMICONDUCTORS. 

Three peaks have been reported in the low energy INS spectrum of hydrogen on platinum black [53]. A peak at 400 cm was assigned to a local mode of vibration of hydrogen on the surface. The peaks at 177 cm and 104 cm corresponded to the INS spectrum of platinum alone observed through the riding modes. 

---