Hydrogen in GaAs

It is worth noticing that, besides silicon, other donors in gallium or arsenic sites can be neutralized as well by hydrogen in GaAs (Pearton et al., 1986). An interesting feature is the dissociation energy trend of... 

At the same time, it was demonstrated that hydrogen neutralization of dopant impurities also occurs in compound semiconductors. This was first achieved with n-type dopants in GaAs (Chevallier etal., 1985) and then with p-type dopants in GaAs (Johnson et al., 1986b). 

Empirically it has been demonstrated that Si (Oehrlein et al., 1981 Pearton et al., 1984b), Ge (Pearton et al., 1984a), and GaAs (Chevallier et al., 1985) can be hydrogenated in simple two electrode (externally biassed) electrochemical cells. In most of these cases, exposures of many minutes were involved cell currents were monitored during treatment but could not be directly used to calculate H influx because of the competing evolution of gaseous H2 ... 

The diffusion of hydrogen in highly or lightly silicon doped GaAs induces a modification of the electrical properties of the material a reduction of the free electron concentration (Fig. 2) and a significant increase of the electron mobility up to values close to the mobility in nonhydrogenated materials with the same net carrier concentration (Jalil et al., 1986 Pan... 

In GaAs, there is a huge number of unidentified deep levels that have been evidenced by DLTS. Some of them depend upon the growth technique. Several works, including early ones, reported the passivation of some of these deep level defects by hydrogenation. 

We will first describe the results obtained for n-type GaAs doped with silicon and then those on p-type GaAs and InP, trying to show how the spectroscopic results correlate with the electrical measurements to provide a consistent picture of the neutralization of dopants by hydrogen in III-V semiconductors. After considerations on the temperature dependence of the widths and positions of the H-related lines, we will discuss the occurrence and origin of other vibration lines associated also with hydrogen in as grown bulk and epitaxial III-V compounds. 

The first H-related line reported in hydrogen-treated doped GaAs was observed in GaAs Si. It was located at 896.82 cm-1 at LHeT and moved at 641.52 cm-1 in the D-treated sample (Jalil et at., 1987). The two lines were labelled 1-H and 1-D respectively. Fig. 12 shows line 1-H with the... 

Several facts can give some suspicion for the origin of the hydrogen contamination in GaAs ... 

Clerjaud et al. (1988b) describe the effect of uniaxial stress applied at low temperatures on the 2001 cm-1 LVM in GaAs. Qualitatively, the effects of the uniaxial stress are the same as those observed by Stavola et al. (1989) on GaAs doped with beryllium and hydrogen and briefly described earlier. 

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