Active solid-state devices (e.g. – transistors – solid-state diode – Thin active physical layer which is – Heterojunction
Reexamination Certificate
1999-02-05
2001-12-18
Jackson, Jr., Jerome (Department: 2815)
Active solid-state devices (e.g., transistors, solid-state diode
Thin active physical layer which is
Heterojunction
C257S015000, C257S017000, C257S025000, C257S598000
Reexamination Certificate
active
06331716
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a variable capacity device having quantum-wave interference layers with an nin or pip junction structure. The present invention also relates to a device with an nn
−
p, np
−
p, or nip junction structure.
2. Description of the Related Art
A voltage-variable capacity device has been known to have a pn junction structure, whose p-layer having a high impurity concentration and n-layer having a low impurity concentration are jointed and form a depletion layer at a boundary region between the p-layer and the n-layer as a capacity device. When a reverse bias voltage is applied to the pn junction of the variable capacity device, a width of the depletion layer is extended and a capacity of the variable capacity device is reduced. Thus the capacity of the device varies according to a value of applied reverse bias voltage.
With respect to the voltage-variable capacity device, it is required to enlarge a variation rate of a capacity value toward an applied voltage. To enlarge the variation rate, forming space distribution in an impurity concentration has been suggested. And to enlarge the voltage variation rate, i.e., voltage-sensitivity, the impurity concentration is required to have a non-linear distribution with respect to a depth.
To obtain the non-linear distribution of the impurity concentration, injecting ions whose acceleration voltage is varied, or a modulation doping in the process of a crystal growth is suggested. But because of a thermal diffusion of impurities, it is difficult to obtain the non-linear distribution as accurate as designed. Thus improvement of the voltage-variation rate of capacity is limited.
SUMMARY OF THE INVENTION
A voltage-variation rate of a depletion layer in the present invention is, therefore, realized not to a variation rate of a distribution of impurity, but to a totally new structure.
It is, therefore, a first object of the present invention to provide a voltage-variable capacity device with high voltage-variation rate, i.e., high voltage sensitivity. It is a second object of the present invention to improve a precision of a capacity controlled by an external voltage. It is a third object to expand a dynamic range of an applied voltage.
In light of these objects a first aspect of the present invention is a variable capacity device with a quantum-wave interference layer, having an nin or pip junction. Each thickness of the first and the second layers is determined by multiplying by an odd number one fourth of a quantum-wave wavelength of carriers, which is conducted in an i-layer, in each of the first and the second layers.
The second aspect of the present invention is to set a kinetic energy of the carriers, which determines the quantum-wave wavelength, near the bottom of a conduction band when the carriers are electrons or near the bottom of a valence band in the second layer, when the carriers are holes.
The third aspect of the present invention is to define each thickness of the first and the second layers as follows:
D
W
=n
W
&lgr;
W
/4=
n
W
h/
4[2
m
W
(
E+V
)]
½
(1)
and
D
B
=n
B
&lgr;
B
/4=
n
B
h/
4(2
m
B
E
)
½
(2)
In Eqs. 1 and 2, h, m
W
, m
B
, E, V, and n
W
, n
B
represent Plank's constant, the effective mass of the conducted carriers in the first layer, effective mass of the conducted carriers in the second layer, the kinetic energy of the carriers at the lowest energy level around the second layer, the potential energy of the second layer relative to the first layer, and odd numbers, respectively.
The fourth aspect of the present invention is a variable capacity device with a quantum-wave interference layer, having an nin or pip junction, and having a plurality of pairs of a first layer and a second layer. The second layer has a wider band gap than the first layer. An i-layer has a partial quantum-wave interference layers I
k
with arbitrary periods T
k
including a first layer having a thickness of n
Wk
&lgr;
Wk
/4 and a second layer having a thickness of n
Bk
&lgr;
Bk
/4. Each of a plural different values E
k
, E
k
+V, &lgr;
Bk
, &lgr;
Wk
, and n
Wk
, n
Bk
represent a kinetic energy of carriers conducted in the second layer, a kinetic energy of carriers conducted in the first layer, a quantum-wave wavelength corresponding energies of the second layer and the first layer, and odd numbers, respectively.
The fifth aspect of the present invention is to form a plurality of quantum-wave interference units in an i-layer in series, each unit having a plurality of pairs of first and second layers.
The sixth aspect of the present invention is to form a carrier accumulation layer at interfaces of the quantum-wave interference units, respectively.
The seventh aspect of the present invention is to form a carrier accumulation layer having the same bandwidth as that of the second layer.
The eighth aspect of the present invention is to determine the respective thicknesses of the first layer and the second layer of each quantum-wave interference layer based on a quantum-wave wavelength of carriers, which are conducted when a predetermined electric field is applied to the i-layer.
The ninth aspect of the present invention is to form a &dgr; layer between the first layer and the second layer which sharply varies in band gap energy from the first and second layers and has a thickness substantially thinner than that of the first and the second layers.
The tenth aspect of the present invention is a variable capacity device with a quantum-wave interference layer, having an nn
−
p, np
−
p, or nip junction. Each thickness of the first and the second layers is determined by multiplying by an odd number one fourth of a quantum-wave wavelength of carriers, which are conducted in an n
−
-layer, a p
−
-layer, or an i-layer, in each of the first and the second layers.
The eleventh aspect of the present invention is to set a kinetic energy of the carriers, which determines the quantum-wave wavelength, near the bottom of a conduction band when the carriers are electrons or near the bottom of a valence band in the second layer, when the carriers are holes.
The twelfth aspect of the present invention is is to define each thickness of the first and the second layers as follows:
D
W
=n
W
&lgr;
W
/4=
n
W
h/
4[2
m
W
(
E+V
)]
½
(3)
and
D
B
=n
B
&lgr;
B
/4=
n
B
h/
4(2
m
B
E
)
½
(4)
In Eqs. 1 and 2, h, m
W
, m
B
, E, V, and n
W
, n
B
represent Plank's constant, the effective mass of the conducted carrier in the first layer, effective mass of the conducted carrier in the second layer, the kinetic energy of the carriers at the lowest energy level around the second layer, the potential energy of the second layer relative to the first layer, and odd numbers, respectively.
The thirteen aspect of the present invention is a variable capacity device with a quantum-wave interference layer, having an nn
−
p, np
−
p, or nip junction, and having a plurality of pairs of a first layer and a second layer. The second layer has a wider band gap than the first layer. An n
−
-layer, p
−
-layer, or i-layer has a partial quantum-wave interference layers I
k
with arbitrary periods T
k
including a first layer having a thickness of n
Wk
&lgr;
Wk
/4 and a second layer having a thickness of n
Bk
&lgr;
Bk
/4. Each of a plural different values E
k
, E
k
+V, &lgr;
Bk
, &lgr;
Wk
, and n
Wk
, n
Bk
represent a kinetic energy of carriers conducted in the second layer, a kinetic energy of carriers conducted in the first layer, a quantum-wave wavelength corresponding energies of the second layer and the first layer, and odd numbers, respectively.
The fourteenth aspect of the present invention is to form a plurality of quantum-wave interference units in an n
−
-layer, p
−
-layer, or i-layer in series, each unit having a plurality of pairs of first and second layers.
The fi
Baumeister Bradley W.
Canare Electric Co., Ltd.
Jackson, Jr. Jerome
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
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