Advanced Diffusion Strategies for Junction Formation in Germanium

Sep 10, 2019, 9:20 AM


Davide De Salvador (University of Padova)


The investigation of innovative dynamical processes for the fabrication of highly doped and
high quality Ge layers is currently a hot topic in many applicative fields such as
nanoelectronics, photonics and radiation detectors. Challenges that require a deep physical
and material science investigation are: i) the high electrical activation in narrow region that
can be obtained by out of equilibrium processes but has not to introduce lattice damage that
may deteriorate the electrical properties. High concentration of the active dopant may
transform germanium in a plasmonic material for sensor applications, or in an optical active
material thanks to the direct gap transition that occurs at high doping and high strain. ii) The
control of the amount of doping at nanoscale (deterministic doping) is fundamental to meet
the request of nanodevices production. Traditional methods as ion implantation are difficult
to manage due to statistical fluctuations. In particular, this task has to be solved in
germanium to exploit such material as a high mobility material in nanoelectronic. iii) The
preservation of the material purity during doping processes is a relevant problem especially
when high purity germanium (HPGe) is used for gamma detector for nuclear spectroscopy
and gamma imaging applications.
In this talk we will present some example of our recent research on germanium to contribute
to the above challenges. Molecular doping process i.e. the production of monolayer selfassembled source of dopants on the devices surface is a promising way toward deterministic
doping. We recently investigate the use of both P and Sb monolayer to this aim [1]. The
effectiveness of such monolayer as diffusion sources is investigated. A very promising way
to obtain very high doping is pulsed laser melting (PLM), this is a highly out equilibrium
process that melt the extreme surface of the crystal and allow for dopant diffusion into the
melt and its incorporation during fast regrowth. The application of this method to Ge allow
for record activation of the dopants. Finally, we investigated the contamination induced by
this laser process in the bulk of the material and we understood that it is a very promising
method for doping of HPGe making possible fast and cheap processing for next generation
gamma detectors [2,3].
[1] F. Sgarbossa et al. , Nanotechnology 29, 465702 (2018).
[2] V. Boldrini et al. J. Phys. D: Appl. Phys. 52 035104 (2018).
[3] G. Maggioni et al. Eur. Phys. J. A 54, 34 (2018).

Topic 4. Diffusive dynamics

Primary author

Davide De Salvador (University of Padova)

Presentation materials

There are no materials yet.