GePb Alloy Growth Using Layer Inversion Method
SEYEDEH FAHIMEH BANIHASHEMIAN,
SEYED AMIR GHETMIRI,
and HAMEED A. NASEEM
1.—Department of Electrical Engineering, University of Arkansas, Fayetteville, AR, USA.
2.—Department of Physics and Chemistry, University of Arkansas at Pine Bluff, Pine Bluff, AR,
USA. 3.—Mechanical Engineering Department, University of Kerbala, Kerbala, Iraq.
4.—Department of Electrical Engineering, Wilkes University, Wilkes-Barre, PA 18766, USA.
5.—Arktonics, LLC, 1339 S. Pinnacle Dr., Fayetteville, AR 72701, USA. 6.—e-mail:
Germanium–lead ﬁlms have been investigated as a new direct-bandgap
group IV alloy. GePb ﬁlms were deposited on Si via thermal evaporation of Ge
and Pb solid sources using the layer inversion metal-induced crystallization
method for comparison with the current laser-induced recrystallization
method. Material characterization of the ﬁlms using x-ray diffraction analysis
revealed highly oriented crystallinity and Pb incorporation as high as 13.5%
before and 5.2% after annealing. Transmission electron microscopy, scanning
electron microscopy, and energy-dispersive x-ray mapping of the samples re-
vealed uniform incorporation of elements and complete layer inversion.
Optical characterization of the GePb ﬁlms by Raman spectroscopy and pho-
toluminescence techniques showed that annealing the samples resulted in
higher crystalline quality as well as bandgap reduction. The bandgap reduc-
tion from 0.67 eV to 0.547 eV observed for the highest-quality material con-
ﬁrms the achievement of a direct-bandgap material.
Key words: Metal-induced crystallization, Si photonics, GePb alloy, x-ray
Group IV alloys have been extensively studied to
enhance the performance of Si technology devices.
Silicon–germanium (SiGe) is one of the most well-
explored group IV alloys. The higher hole mobility
and lattice size of Ge along with the narrower
bandgap enable fabrication of new devices such as
SiGe heterojunction bipolar transistors,
nel metal–oxide–semiconductor ﬁeld-effect transis-
SiGe source/drain stressors,
On the other hand, cutting-edge
advances in incorporation of Sn into the Ge lattice
have resulted in the ﬁrst group IV direct-bandgap
material, opening the new ﬁeld of group IV photon-
ics, where optoelectronic devices can be monolithi-
cally incorporated onto Si chips.
and fabrication of devices such
as light-emitting diodes (LEDs),
using GeSn technology
are all attainable in a complementary–metal–oxide
semiconductor-compatible process. However,
achieving a direct bandgap using Sn requires incor-
poration of 8% to 10% Sn,
and in many devices
Therefore, identiﬁcation of new
group IV alloys that require less structural change
is signiﬁcantly essential and could open new routes
to achieve the goals of silicon photonics more easily.
Due to the similarities between Sn and Pb, the last
stable element in group IV, investigation of GePb
alloy is of great importance.
GeSn alloy has been extensively studied over the
last 10 years, but other group IV alloys such as
(Received July 13, 2017; accepted March 14, 2018;
published online April 9, 2018)
Journal of ELECTRONIC MATERIALS, Vol. 47, No. 7, 2018
2018 The Minerals, Metals & Materials Society