1. A method for producing an epitaxial wafer including a substrate composed of a III-V compound semiconductor and an epitaxial layer structure that is composed of a III-V compound semiconductor, includes a diffusive-concentration-distribution-adjusting layer and a window layer, and is disposed on the substrate, the method comprising:
a step of growing an antimony-containing layer on the substrate by metal-organic vapor phase epitaxy using only metal-organic sources; and a step of growing, on the antimony-containing layer, an antimony-free layer including the diffusive-concentration-distribution-adjusting layer and the window layer,
wherein, from the growth of the antimony-containing layer to completion of the growth of the window layer, the growth is performed at a growth temperature of 425\xb0 C. or more and 525\xb0 C. or less,
wherein the substrate is an InP substrate; an InP window layer is grown as the window layer; and, from initiation of the growth of the antimony-containing layer to completion of the growth of the InP window layer, the growth is continuously performed in the same growth chamber by the metal-organic vapor epitaxy using only metal-organic sources such that an interface formed between the diffusive-concentration-distribution-adjusting layer and the InP window layer has an oxygen concentration and a carbon concentration that are less than 1\xd71017 cm\u22123.
2. The method for producing an epitaxial wafer according to claim 1, wherein growth temperature for the window layer is at least 25\xb0 C. lower than growth temperature for a layer ranging from the antimony-containing layer to a layer directly under the window layer.
3. The method for producing an epitaxial wafer according to claim 1, wherein the antimony-containing layer is a multilayer constituted by one or both of a pair of layers forming a multiple-quantum well structure (MQW).
4. The method for producing an epitaxial wafer according to claim 1, wherein, in the epitaxial layer structure, a type-II MQW constituted by InxGa1-xAs (0.38\u2266x\u22660.68) and GaAs1-ySby (0.36\u2266y\u22661.00) or a type-II MQW constituted by Ga1-uInuNvAs1-v (0.4\u2266u\u22660.8, 0<v\u22660.2) and GaAs1-ySby (0.36\u2266y\u22661.00) is grown.
5. A method for producing a photodiode from an epitaxial wafer produced by the production method according to claim 1, the antimony-containing layer serving as entirety of or a part of an absorption layer, the method comprising: a step of forming a selective diffusion mask pattern on the window layer of the epitaxial wafer; and a step of selectively diffusing an impurity from the window layer exposed through an opening of the selective diffusion mask pattern such that the impurity reaches the absorption layer.
6. An epitaxial wafer comprising: a substrate composed of a III-V compound semiconductor; and an epitaxial layer structure that is composed of a III-V compound semiconductor, includes a diffusive-concentration-distribution-adjusting layer and a window layer, and is disposed on the substrate, wherein
the epitaxial layer structure includes an antimony-containing layer and, on the antimony-containing layer, an antimony-free layer including the diffusive-concentration-distribution-adjusting layer and the window layer,
a density of protruding surface defects having a height of 10 \u03bcm or more in the window layer is 0.05 defects cm\u22122 or more and 1.25 defects cm\u22122 or less, and the antimony-containing layer and the antimony-free layer have a carbon concentration of 5\xd71015 cm\u22123 or less,
wherein the substrate is an InP substrate; the window layer is an InP window layer; and an interface between the diffusive-concentration-distribution-adjusting layer and the InP window layer has an oxygen concentration and a carbon concentration that are less than 1\xd71017 cm\u22123.
7. The epitaxial wafer according to claim 6, wherein the antimony-containing layer is a multilayer constituted by one or both of a pair of layers forming a multiple-quantum well structure (MQW).
8. The epitaxial wafer according to claim 6, wherein the antimony-containing layer is a GaAs1-ySby multilayer in a type-II MQW constituted by InxGa1-xAs (0.38\u2266x\u22660.68) and GaAs1-ySby (0.36\u2266y\u22661.00) or a GaAs1-ySby multilayer in a type-II MQW constituted by Ga1-uInuNvAs1-v (0.4\u2266u\u22660.8, 0<v\u22660.2) and GaAs1-ySby (0.36\u2266y\u22661.00).
9. A photodiode comprising the epitaxial wafer according to claim 6, wherein the antimony-containing layer serves as entirety of or a part of an absorption layer, a selective diffusion mask pattern is disposed on the window layer, and an impurity is distributed from the window layer exposed through an opening of the selective diffusion mask pattern such that the impurity reaches the absorption layer.
10. An optical sensor device comprising the photodiode according to claim 9.
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. A fuel cell comprising:
a membrane electrode assembly comprising an electrolyte membrane, and an anode electrode and a cathode electrode provided on both sides of the electrolyte membrane;
a diffusion layer for supplying the cathode electrode with air, disposed at a cathode electrode side of the membrane electrode assembly; and
an air introducing inlet for supplying the diffusion layer with the air,
wherein when a total effective area of the electrolyte membrane at the cathode electrode side is A cm2, an average current density in an operation state of the fuel cell is I Acm2, and a total area of the air introducing inlet is S cm2, a relation of A\xd7I\xd70.5<S<A\xd7I\xd72.0 is satisfied.
2. A fuel cell according to claim 1, further comprising an air introducing layer parallel to the electrolyte membrane, wherein the air introducing layer has two faces thereof opposed to each other and opened to the atmosphere for flowing air, and wherein when a length of the electrolyte membrane of the fuel cell is L cm, an average current density in an operation state of the fuel cell is I Acm2, and a width of a gap as the air introducing layer is w cm, a relation of I\xd7L\xd70.25<w<I\xd7L\xd71.0 is satisfied.
3. A fuel cell comprising:
a membrane electrode assembly comprising an electrolyte membrane, and an anode electrode and a cathode electrode provided on both sides of the electrolyte membrane;
a diffusion layer for supplying the cathode electrode with air, disposed at a cathode electrode side of the membrane electrode assembly; and
an air introducing inlet for supplying the diffusion layer with the air,
wherein when a total effective area of the electrolyte membrane at the cathode electrode side is A cm2, and a total area of the air introducing inlet is S cm2, a relation of A\xd70.2<S<A\xd70.8 is satisfied.
4. A fuel cell according to claim 3, further comprising an air introducing layer parallel to the electrolyte membrane, wherein the air introducing layer has two faces thereof opposed to each other and opened to the atmosphere for flowing air, and wherein a length of the electrolyte membrane of the fuel cell is L cm, and a width of a gap as the air introducing layer is w cm, a relation of L\xd70.1<w<L\xd70.4 is satisfied.