NOVEMBER 2022 I DESIGN007 MAGAZINE 37
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References
1. A Manual of Engineering Drawing for Students
and Draftsmen, 9th Ed., by French & Vierck, 1960,
p. 487.
Stephen V. Chavez is senior
product marketing manager,
Siemens EDA, and chairman of
PCEA. To read past columns,
click here.
The carrier concentration and conductivity in
p-type monovalent copper semiconductors can be
significantly enhanced by adding alkali metal impu-
rities, as shown recently by Tokyo Tech researchers.
Doping with isovalent and larger-sized alkali metal
ions effectively increased the free charge carrier
concentration and the mechanism was unraveled
by their theoretical calculations. Their carrier dop-
ing technology enables high carrier concentration
and high mobility p-type thin films to be prepared
from the solution process, with photovoltaic device
applications.
To propose a new carrier doping design for
p-type doping in CuI, researchers from Japan and
USA recently focused on the alkali impurity effect,
which has been empirically used for hole doping in
copper monovalent semiconductors, copper oxide
(Cu
2
O) and Cu(In,Ga)Se
2
.
In a novel approach outlined in a study published
in the Journal of the American Chemical Society,
the team, led by Dr. Kosuke Matsuzaki from Tokyo
Institute of Technology (Tokyo Tech), Japan, dem-
onstrated experimentally that p-type doping with
alkali ion impurities, which has the same valence as
copper but larger size, can improve conductivity in
Cu(I)-based semiconductors. The theoretical analy-
ses show that the complex defects, which are com-
posed of alkali ion impurity and vacancies of cop-
per ions, are an origion of hole generation (p-type
conductivity).
Based on the p-type doping mechanism to form
acceptor-type Cu vacancy defect complex, the
team investigated larger alkaline ions, such as
potassium, rubidium, and cesium (Cs), as acceptor
impurities in γ-CuI.
Indeed, the development could be a major leap
forward for copper(I)-based semiconductors, and
could soon lead to their practical applications in
solar cells and optoelectronic devices.
(Source: Tokyo Institute of Technology)
Novel Carrier Doping in p-type Semiconductors
