<s>
A	O
resonant-tunneling	B-Algorithm
diode	I-Algorithm
(	O
RTD	O
)	O
is	O
a	O
diode	O
with	O
a	O
resonant-tunneling	O
structure	O
in	O
which	O
electrons	O
can	O
tunnel	O
through	O
some	O
resonant	O
states	O
at	O
certain	O
energy	O
levels	O
.	O
</s>
<s>
The	O
structure	O
and	O
fabrication	O
process	O
of	O
Si/SiGe	O
resonant	O
interband	O
tunneling	O
diodes	O
are	O
suitable	O
for	O
integration	O
with	O
modern	O
Si	O
complementary	O
metal	O
–	O
oxide	O
–	O
semiconductor	O
(	O
CMOS	B-Device
)	O
and	O
Si/SiGe	O
heterojunction	O
bipolar	O
technology	O
.	O
</s>
<s>
When	O
a	O
voltage	O
is	O
placed	O
across	O
an	O
RTD	O
,	O
a	O
terahertz	B-Architecture
wave	I-Architecture
is	O
emitted	O
,	O
which	O
is	O
why	O
the	O
energy	O
value	O
inside	O
the	O
quantum	O
well	O
is	O
equal	O
to	O
that	O
of	O
the	O
emitter	O
side	O
.	O
</s>
<s>
As	O
voltage	O
is	O
increased	O
,	O
the	O
terahertz	B-Architecture
wave	I-Architecture
dies	O
out	O
because	O
the	O
energy	O
value	O
in	O
the	O
quantum	O
well	O
is	O
outside	O
the	O
emitter	O
side	O
energy	O
.	O
</s>
<s>
Advances	O
in	O
the	O
MBE	B-Algorithm
technique	O
led	O
to	O
observation	O
of	O
negative	O
differential	O
conductance	O
(	O
NDC	O
)	O
at	O
terahertz	O
frequencies	O
,	O
as	O
reported	O
by	O
Sollner	O
et	O
al	O
.	O
</s>
<s>
Resonant	B-Algorithm
tunneling	I-Algorithm
diodes	I-Algorithm
are	O
typically	O
realized	O
in	O
III-V	O
compound	O
material	O
systems	O
,	O
where	O
heterojunctions	O
made	O
up	O
of	O
various	O
III-V	O
compound	O
semiconductors	O
are	O
used	O
to	O
create	O
the	O
double	O
or	O
multiple	O
potential	O
barriers	O
in	O
the	O
conduction	O
band	O
or	O
valence	O
band	O
.	O
</s>
<s>
Reasonably	O
high	O
performance	O
III-V	O
resonant	B-Algorithm
tunneling	I-Algorithm
diodes	I-Algorithm
have	O
been	O
realized	O
.	O
</s>
<s>
Such	O
devices	O
have	O
not	O
entered	O
mainstream	O
applications	O
yet	O
because	O
the	O
processing	O
of	O
III-V	O
materials	O
is	O
incompatible	O
with	O
Si	O
CMOS	B-Device
technology	O
and	O
the	O
cost	O
is	O
high	O
.	O
</s>
<s>
Resonant	B-Algorithm
tunneling	I-Algorithm
diodes	I-Algorithm
can	O
also	O
be	O
realized	O
using	O
the	O
Si/SiGe	O
materials	O
system	O
.	O
</s>
<s>
However	O
,	O
the	O
performance	O
of	O
Si/SiGe	O
resonant	B-Algorithm
tunneling	I-Algorithm
diodes	I-Algorithm
was	O
limited	O
due	O
to	O
the	O
limited	O
conduction	O
band	O
and	O
valence	O
band	O
discontinuities	O
between	O
Si	O
and	O
SiGe	O
alloys	O
.	O
</s>
<s>
Resonant	O
interband	O
tunneling	O
diodes	O
(	O
RITDs	O
)	O
combine	O
the	O
structures	O
and	O
behaviors	O
of	O
both	O
intraband	O
resonant	B-Algorithm
tunneling	I-Algorithm
diodes	I-Algorithm
(	O
RTDs	O
)	O
and	O
conventional	O
interband	O
tunneling	O
diodes	O
,	O
in	O
which	O
electronic	O
transitions	O
occur	O
between	O
the	O
energy	O
levels	O
in	O
the	O
quantum	O
wells	O
in	O
the	O
conduction	O
band	O
and	O
that	O
in	O
the	O
valence	O
band	O
.	O
</s>
<s>
Like	O
resonant	B-Algorithm
tunneling	I-Algorithm
diodes	I-Algorithm
,	O
resonant	O
interband	O
tunneling	O
diodes	O
can	O
be	O
realized	O
in	O
both	O
the	O
III-V	O
and	O
Si/SiGe	O
materials	O
systems	O
.	O
</s>
<s>
The	O
same	O
structure	O
was	O
duplicated	O
by	O
another	O
research	O
group	O
using	O
a	O
different	O
MBE	B-Algorithm
system	O
,	O
and	O
PVCRs	O
of	O
up	O
to	O
6.0	O
have	O
been	O
obtained	O
.	O
</s>
<s>
Integration	O
of	O
Si/SiGe	O
RITDs	O
with	O
Si	O
CMOS	B-Device
has	O
been	O
demonstrated	O
.	O
</s>
