Active solid-state devices (e.g. – transistors – solid-state diode – Including semiconductor material other than silicon or... – Group iii-v compound
Reexamination Certificate
2002-09-10
2004-05-04
Eckert, George (Department: 2815)
Active solid-state devices (e.g., transistors, solid-state diode
Including semiconductor material other than silicon or...
Group iii-v compound
C257S190000, C257S192000, C257S201000, C148S033400, C117S101000
Reexamination Certificate
active
06730987
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a technique for fabricating a compound semiconductor device using a silicon (Si) single crystal substrate having a specific azimuth with respect to the plane of the substrate.
As one of Group III-V compound semiconductors, a boron phosphide (BP)-base Group Ill-V compound semiconductor (boron phosphide-base semiconductor) containing boron (B) and phosphorus (P) as constituent elements is known (see, Iwao Teramoto,
Handotai Device Gairon
(
Introduction of Semiconductor Device
), 1st ed., pp. 26-28, Baifukan (Mar. 30, 1995)). The boron phosphide (BP) has a small Philips ionicity of 0.006 (see, Philips,
Handotai Ketsugo Ron
(
Bonds and Bands in Semiconductors
), 3rd imp., page 51, Yoshioka Shoten (Jul. 25, 1985)) and is a substance almost comprising a covalent bond. Furthermore, this is a zinc-blende type cubic crystal and therefore, has a band structure of degenerate valence band (see, Toshiaki Ikoma and Hideaki Ikoma,
Kagobutsu Handotai no Kiso Bussei Nyumon
(
Guide for Basic Physical Properties of Compound Semiconductor
), 1st ed., pp. 14-17, Baifukan (Sep. 10, 1991)). By virtue of this, boron phosphide is advantageous in that a p-type electrically conducting layer can be readily formed.
Conventionally, various compound semiconductor devices are fabricated by using a boron phosphide layer provided on a silicon (Si) single crystal substrate. For example, a hetero-bipolar transistor (HBT) using a boron phosphide layer is known (see,
J. Electrochem. Soc.,
125(4), pp. 633-637 (1978)). Also, a solar cell using a boron phosphide layer as the window layer is known (see,
J. Electrochem. Soc.
, supra). Furthermore, techniques for fabricating a blue-band or green-band light emission diode (LED) or laser diode (LD) using boron phosphide and a mixed crystal thereof are disclosed (see, Japanese Patents (1) 2809690, (2) 2809691 and (3) 2809692, and (4) U.S. Pat. No. 6,069,021).
The lattice constant of a monomer boron phosphide (BP, boron monosphosphide) is about 4.538 Å (see,
Handotai Device Gairon
(
Introduction of Semiconductor Device
), supra, page 28). On the other hand, the silicon (Si) single crystal used as the substrate is also a zinc-blende type cubic crystal and the lattice constant thereof is about 5.431 Å (see,
Handotai Device Gairon
(
Introduction of Semiconductor Device
), supra, page 28). Accordingly, the lattice mismatch degree expressed by the ratio of difference (=0.893 Å) in the lattice constant of both crystals to the lattice constant (=5.431 Å) of silicon single crystal is as large as about 16.6%. In order to prevent peeling of the boron phosphide layer from the Si substrate surface due to this large lattice mismatch degree, technical means of providing a low-temperature buffer layer on the Si substrate surface is disclosed, where the buffer layer comprises a polycrystalline boron phosphide containing an amorphous portion grown at a relatively low temperature (see, U.S. Pat. No. 6,069,021, supra).
In conventional techniques, the boron phosphide-base semiconductor layer is formed using, for example, a silicon single crystal having a surface of {100} or {111} crystal plane as the substrate (see, U.S. Pat. No. 6,069,021, supra). In particular, silicon atoms are densely present on the {111} crystal plane as compared with {100} crystal plane and this is considered effective for preventing boron (B) and phosphorus (P) constituting the low-temperature buffer layer from penetrating into the inside of the silicon single crystal substrate.
However, the distance between {111} crystal planes of the silicon single crystal is about 3.136 Å, whereas the distance of {110} crystal planes of boron phosphide (BP, lattice constant=4.538 Å) is 3.209 Å and does not agree with the distance between {111} crystal planes of the silicon single crystal. Therefore, the boron phosphide layer provided on a conventional silicon single crystal substrate having a surface of {111} crystal plane is disadvantageously a poor-quality crystal layer containing a large amount of crystal defects such as dislocation or stacking fault.
The present invention provides a technique for giving a boron phosphide-base semiconductor layer having excellent crystallinity by using a silicon single crystal substrate having a surface such that the distance between {111} crystal planes of silicon intersecting with the surface of {111} silicon single crystal agrees with the distance between {110} crystal planes of boron phosphide.
BRIEF SUMMARY OF THE INVENTION
The object of the present invention is to solve the above-described problems in conventional techniques by specifying the azimuth of the crystal plane constituting the surface of a silicon single crystal substrate. More specifically, the present invention provides the following embodiments:
(1) a compound semiconductor device comprising a silicon (Si) single crystal substrate having provided on the surface thereof a boron phosphide (BP)-base semiconductor layer containing boron (B) and phosphorus (P) as constituent elements, wherein the surface of the silicon single crystal substrate is a {111} crystal plane inclined at an angle of 5.0° to 9.0° toward the <110> crystal azimuth;
(2) the compound semiconductor device as describe in (1) above, wherein the surface of the silicon single crystal substrate is a {111} crystal plane inclined at an angle of 7.3±0.5° toward the <110> crystal azimuth;
(3) the compound semiconductor device as described in (1) above, which comprises a stacked layer structure such that a boron phosphide-base semiconductor layer having a {110} crystal plane is stacked on a silicon single crystal substrate having a surface of {111} crystal plane inclined at an angle of 5.0° to 9.0° toward the <110> crystal azimuth, through a low-temperature buffer layer composed of a boron phosphide-base semiconductor layer;
(4) the compound semiconductor device as described in (2) above, which comprises a stacked layer structure such that a boron phosphide (BP) semiconductor layer having a {110} crystal plane is stacked on a silicon single crystal substrate having a surface of {111} crystal plane inclined at an angle of 7.3±0.5° toward the <110> crystal azimuth, through a low-temperature buffer layer composed of a boron phosphide-base semiconductor layer;
(5) a light-emitting device comprising the compound semiconductor device described in any one of (1) to (4) above; and
(6) a transistor comprising the compound semiconductor device described in any one of (1) to (4) above.
Furthermore, the present invention provides the following embodiments:
(7) a method for producing a compound semiconductor device, comprising stacking a boron phosphide-base semiconductor layer having a {110} crystal plane on a silicon single crystal substrate having a surface of {111} crystal plane inclined at an angle of 5.0° to 9.0° toward the <110> crystal azimuth, through a low-temperature buffer layer composed of a boron phosphide-base semiconductor layer; and
(8) a method for producing a compound semiconductor device, comprising stacking a boron phosphide (BP) semiconductor layer having a {110} crystal plane on a silicon single crystal substrate having a surface of {111} crystal plane inclined at an angle of 7.3±0.5° toward the <110> crystal azimuth, through a low-temperature buffer layer composed of a boron phosphide-base semiconductor layer.
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patent: 4963508 (1990-10-01), Umeno et al.
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