Hydrogen incorporation in n-type Si-doped GaAs epilayers is a well-known process which
leads to the neutralization of the active Si impurities with the formation of SiH complexes.
Recently, we have shown that SiH complex dissociation and, consequently, Si-dopant
reactivation could occur when the epilayers are exposed to an electron beam.
Two epilayers have been studied: the first is a
0.35 µm
thick hydrogenated Si-doped GaAs epilayer and the second is Si planar-doped
AlGaAs/GaAs/InGaAs heterostructures.
Firstly, Hall effect measurements have been carried out on the epilayers exposed, after RF
hydrogen plasma exposition, to increasing electron doses with different injection
energies. For the 2D heterostructures, we have observed that the free carrier density
Ns does not
vary significantly for weak electron densities. This reactivation presents a threshold value, contrary to the
0.35 µm epilayer
in which Ns
varies quite linearly. It will be shown that such phenomena might be attributed to the
filling of surface states as the dopants are progressively reactivated.
Then, using a high spatial resolution electron beam lithography system, nanometric
conductive patterns have been fabricated starting from hydrogenated epilayers. Electric
measurements have been performed and the results obtained show that about 15 nm spatial
resolution could be expected.
In conclusion, taking into account this spatial resolution, the high spatial contrast of
conductivity which could be expected due to the existence of an electron dose
threshold, and the high mobility of the AlGaAs/GaAs/InGaAs heterostructure,
the effects described in this paper could open a new way for the fabrication of
III–V 1D or 2D mesoscopic structures for electronic or optoelectronic applications.