1. A gallium nitride type epitaxial crystal for field effect transistor, comprising:
a base substrate,
(a) a gate layer,
(b) a high purity first buffer layer containing a channel layer contacting an interface on the base substrate side of the gate layer,
(c) a second buffer layer arranged on the base substrate side of the first buffer layer,
(d) a non-gallium nitride type insulating layer arranged on the base substrate side of the second buffer layer, and having an opening at a part thereof, and
(e) a p-conductive type semiconductor crystal layer arranged on the base substrate side of the insulating layer,
wherein a connection layer comprising a gallium nitride type crystal is arranged in the opening of the non-gallium nitride type insulating layer to electrically connect the first buffer layer and the p-conductive type semiconductor crystal layer.
2. The crystal of claim 1, wherein the connection layer is a p-conductive type crystal.
3. The crystal of claim 1, wherein the connection layer has an end extending toward the first buffer layer, and the end does not extend beyond the first buffer layer.
4. The crystal of claim 1, wherein the connection layer is a crystal layer grown by selective growth on the p-conductive type semiconductor crystal layer exposed at the opening of the non-gallium nitride type insulating layer.
5. The crystal of claim 1, wherein the first buffer layer has an average dislocation density of 1\xd7105cm or less, except for the upper part of the opening of the non-gallium nitride type insulating layer.
6. The crystal of claim 1, wherein at least a part of the second buffer layer is a crystal layer formed by a selective lateral growth method using the gallium nitride type crystal provided in the opening as a base point.
7. The crystal of claim 1, wherein the insulating layer comprises silicone oxide or silicon nitride.
8. A field effect transistor formed using the crystal of claim 1, comprising:
a gate electrode arranged on an upper part of a gate layer, and
a source electrode and a drain electrode, arranged on both sides of the gate electrode and connected to the gate layer by ohmic connection,
wherein the opening or the connection layer formed in the opening is arranged so as to face the lower part of the source electrode, or the region between the source side edge of the gate electrode and the source electrode, and
the p-conductive type semiconductor crystal layer is connected to a hole-withdrawing electrode.
9. The field effect transistor of claim 8, wherein the second buffer layer is a crystal layer grown by a lateral growth method.
10. The field effect transistor of claim 8, wherein the interface between the first buffer layer and the gate layer is constituted of a semiconductor heterojunction interface.
11. A method for producing a gallium nitride type epitaxial crystal, comprising:
(i) a step of epitaxial growth of a p-conductive type semiconductor crystal layer onto a base substrate;
(ii) a step of formation of an insulating layer on the p-conductive type semiconductor crystal layer;
(iii) a step of formation of an opening in the insulating layer; and
(iv) a step of growth of a connection layer for electrically connecting the p-conductive type semiconductor crystal layer and a first buffer layer, in the opening using the insulating layer as a mask.
12. The method of claim 11, further comprising:
(v) a step of growth of a crystal layer by a selective lateral growth method using the gallium nitride type crystal grown in the opening as a base point on the insulating layer after growth of the connection layer.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. An apparatus for regulating the flow of a gas between a high-pressure zone and a zone of lower pressure, said apparatus comprising:
a hollow body having an axis;
a first chamber and a second chamber, said chambers defined within said body;
a nozzle within said body and separating said chambers, said nozzle defining a passage for the passage of gas between said chambers; and
a stem movable axially within said passage, extending at least partially into said first chamber, wherein axial movement of said stem varies the position of said stem in relation to said nozzle, said stem comprising:
an o-ring seat disposed in an annular pocket on said stem and contactable with said nozzle to seal said passage against the passage of gas;
a distal stem portion extending at least partially into said first chamber and a proximate stem portion within said second chamber and extending into said passage, said distal stem portion connectable to said proximate stem portion to squeeze at least part of said o-ring there-between; and
an axial duct defined in said stem for venting said gas into an interior portion of said pocket;
wherein said axial duct comprises a central duct in said proximate stem portion in linear registration, and fluid communication, with a central duct in said distal stem portion.
2. An apparatus according to claim 1 further comprising at least one branch duct defined in said distal stem portion, said at least one branch duct extending generally radially between said central duct in said distal stem portion and said interior portion of said pocket, wherein said gas flows through said at least one branch duct for balancing pressures between said pocket and said second chamber.
3. An apparatus according to claim 1 wherein when connected, said distal stem portion and said proximate stem portion define at least a portion of said annular pocket for receiving said o-ring.
4. An apparatus according to claim 1 further comprising an internal component insertable into said distal stem portion and said proximate stem portion for joining said stem portions together, said internal component comprising:
a longitudinal central duct along the length of said internal component;
an exterior seat portion for receiving thereon said o-ring;
an external groove in fluid communication with said longitudinal central duct and with said exterior seat portion, wherein said gas flows along said groove for balancing pressures between said pocket and said second chamber.
5. An apparatus for regulating the flow of a gas between a high-pressure zone and a zone of lower pressure, said apparatus comprising:
a hollow body having an axis;
a first chamber and a second chamber defined within said body;
a nozzle within said body and separating said chambers, said nozzle defining a passage for the passage of gas between said chambers; and
a stem movable axially within said passage and comprising:
a distal portion extending at least partially into said first chamber;
a proximate portion at least partially within said second chamber and extending into said passage, wherein axial movement of said stem varies the position of said proximate portion in relation to said nozzle;
an o-ring seat disposed in a pocket defined in said stem and contactable with said nozzle to seal said passage against the passage of gas; and
vent means for balancing pressures between said pocket and said second chamber only, said vent means comprising a single axial duct defined in said stem between said second chamber and an interior portion of said pocket.
6. An apparatus according to claim 5, wherein said distal stem portion extends at least partially into said first chamber and said proximate stem portion is movable within said second chamber and extends into said passage, said distal stem portion connectable to said proximate stem portion to squeeze at least part of said o-ring in said pocket.
7. An apparatus according to claim 6 wherein said axial duct comprises a central duct in said proximate stem portion in linear registration, and fluid communication, with a central duct in said distal stem portion.
8. An apparatus according to claim 7 further comprising at least one branch duct defined in said distal stem portion, said at least one branch duct extending generally radially between said central duct in said distal stem portion and said interior portion of said pocket, wherein said gas flows through said at least one branch duct for balancing pressures between said pocket and said second chamber.
9. An apparatus for regulating the flow of a gas between a high-pressure zone and a zone of lower pressure, said apparatus comprising:
a hollow body having an axis;
a first chamber and a second chamber, said chambers defined within said body;
a nozzle within said body and separating said chambers, said nozzle comprising a convexly curved wall, and defining a passage for the passage of gas between said chambers; and
a stem movable axially within said passage and comprising:
a distal portion extending at least partially into said first chamber;
a proximate portion within said second chamber and extending into said passage, wherein axial movement of said stem varies the position of said proximate portion in relation to said nozzle; and
an o-ring seat in a pocket between said proximate portion and said distal portion of said stem and contactable with said nozzle to seal said passage against the passage of gas; and
an axial duct for balancing pressures between an interior of said pocket and said second chamber;
wherein said pocket interior is substantially isolated from said first chamber.