Sn doped
-Ga
2
O
3
: deep UV transparent conductor
E.Chikoidze
1*
, K.Akaiwa
2
, K.Kaneko
2
, S.Fujita
2
, H.J. von Bardeleben
3
Y.Dumont
1
1
GEMaC, UVSQ– CNRS, Paris Saclay University, Versailles, France
2
Department of Electronic Science and Engineering, Kyoto University, Kyoto, Japan
3
Sorbonne Universités, UPMC Université Paris 6, Institut des Nanosciences de Paris, France
Ga
2
O
3
is a wide band gap semiconductor which occurs in different polytypes
(
,
,
,
,
). The polytype
-Ga
2
O
3
, which is the stable form of Ga
2
O
3
from room temperature
up to its melting point, has already attracted attention more than half century ago due to its
interesting optical and electrical properties: transparency in the deep UV and high n-type
conductivity
1
. Very recently
-Ga
2
O
3
has become the object of intense research as it has been
shown to be of high technological interest and has given rise to successful realization of
microelectronic devices such as transparent field-effect transistor, high power devices,
photodetectors and photodiodes
1-4
.
Our work is dedicated to Ga
2
O
3 ,
in the
- phase, one of the five phases known as thermally
semi- stable. Highly crystalline Sn doped Ga
2
O
3
thin films were synthesised by the mist CVD
method.
6
We performed detailed studies of the influence of the Sn donor dopant on the
optical and electrical properties of
-Ga
2
O
3
. Absorption coefficient and optical band gaps
were estimated for the samples with different Sn concentrations, showing that doping does
not deteriorate the UV-VIS-NIR transparency of the material.
Resistivity and Hall effect measurements were done in 2K-500K temperature range and up to
9T magnetic field. The temperature dependence of the electrical conductivity shows that by
varying the Sn donor concentration Ga
2
O
3
can pass from insulator to a material with metallic
conductivity. Photoconductivity was studied as well. Different value and sign of
magnetoresitance were measured for insulating, mixed and degenerated phases. By ESR
spectroscopy we have determined the spin S=1/2 state and C
3V
point symmetry of the neutral
Sn donor in a good agreement with the model of a simple Sn
Ga
center.
1.K.Matsuaki, H.Hiramatsu, K.Nomura, H.Yanagi, T.Kamiya, M.Hirano, H.Hosono, Thin
films, 496,37, 2006
2M.Higashiwaki, K.sasaki, A.Kuramata, T.Masui, S.Yamakoshi, Appl.phys.lett.100,
,013504, 2012
3. M.Zhong,Zh.Wei, X.Meng, F.Wu, J.Li, J.Alloys and compounds, 619, 572, 2015
4. S.Nakagomi, T.Momo, S.Takahashio, Y.Kokubun, Appl.Phys.Lett, 103,072105, 2013
5.K.Akaiwa and S.Fujita, Jpn.J appl.Phys. 51, 070203, 2012
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