Production of InP Single-Crystal Body An InP single-crystal body is grown by the VB method. As shown in FIG. 1, two heaters 24a, 24b are used and one inter-heater gap 24abo is provided. Closure plate 25 com-posed of PBN is placed between an InP polycrystal body having a purity of 99.9 mass % and serving as InP source material 13 and B₂O₃ serving as sealing member 23. The closure ratio (percentage of the area of the closure plate with respect to the cross sectional area of the straight body portion of crucible 21 perpendicular to the axial direction) of closure plate 25 is set to 97%. The InP single-crystal body is grown by adjusting a temperature distribution in the crucible to attain a temperature of 1065° C. at a surface of the InP source material and attain a temperature gradient of 2° C./cm at a crystal growth interface in a crystal growth direction.

Production of InP Single-Crystal substrate The outer circumference of the obtained InP single-crystal body was ground and the obtained InP single-crystal body was sliced along a plane perpendicular to the crystal growth direction. Then, the main surface thereof was subjected to mechanical polishing and chemical mechanical polishing (CMP), thereby producing InP single-crystal substrates each having a diameter of 100 mm and a thickness of 525 µm. The oxygen concentration of each of the obtained InP single-crystal substrates is measured by CPAA (Charged Particle Activation Analysis), the thickness of an oxide film formed in the main surface is measured by a spectral ellipsometer (PCA ellipsometer SE-101 provided by Photonic Lattice), and a dislocation density thereof is measured in an optical microscope image (BH₂-UMA provided by Olympus). Fur-ther, emission intensities of oxygen defect centers in the InP crystal substrate are measured by a cathode luminescence measuring device (MonoCL₄ provided by Gatan). Results are collectively shown in Table 1. Here, in the CPAA for the oxygen concentration, 18F is used which is generated by a nuclear reaction between 3He and oxygen, 16O, in the InP crystal body and which undergoes β' decay with a half-life of 109.73 minutes. The InP crystal body having been irradiated with 3He is melted with an acid, and 18F generated by way of a KBF₄ (potassium tetrafluoroborate) precipitation method is chemically sepa-rated. Gamma rays of 511 keV, which are generated by positron annihilation upon the β' decay of 18F, are measured using a NaI detector to determine the number of counts for 10 a specified time after the end of the irradiation by the least squares method. The number of counts after the specified time as determined using a standard sample, SiO2, in the same manner is used for correction, thereby converting it to the oxygen concentration. Moreover, a peak emission intensity (emission wave-length: around 1078 nm) of the oxygen defect centers in the InP crystal substrate is measured at a room temperature (25° C.) with the cathode luminescence (acceleration voltage: kV; electron current: 0.4 nA; beam diameter: 10 nm), whereby an amount of the oxygen defect centers in the InP crystal substrate can be evaluated. When the amount of the oxygen defect centers is smaller than 500 counts/sec, the emission intensity of the oxygen defect centers in the InP crystal substrate is regarded as “Small”. When the amount of the oxygen defect centers is larger than 5000 counts/sec, the emission intensity of the oxygen defect centers in the InP crystal substrate is regarded as “Large”. When the amount of the oxygen defect centers is more than or equal to 500 counts/sec and less than or equal to 5000 counts/sec, the emission intensity of the oxygen defect centers in the InP crystal substrate is regarded as “Appropriate”. When the emission intensity of the oxygen defect centers in the InP crystal substrate is not “Large” and “Small” but is “Appro-priate”, growth from the oxygen defect centers is facilitated during the crystal growth and therefore abnormal defects are less likely to be generated. “Small” is the second most preferable to “Appropriate”. In the case of “Large”, electron mobility in the InP single-crystal body becomes low, thus resulting in decreased characteristics of a device including the InP single-crystal substrate. The invention claimed is:

An indium phosphide single-crystal substrate, wherein: the indium phosphide single-crystal substrate has a CPAA oxygen concentration of more than or equal to 5.5×1015 atoms·cm⁻³ and less than 1×1016 atoms·cm⁻³, the CPAA oxygen concentration being an oxygen concen-tration measured by means of a Charged Particle Acti-vation Analysis (CPAA) that measures oxygen concen-tration using 18F which is generated by a nuclear reaction between 3He and 16O in the indium phosphide single-crystal substrate and which undergoes β+ decay with a half-life of 109.73 minutes; and a diameter of the indium phosphide single-crystal substrate is more than or equal to 100 mm and less than or equal to 150 mm.

Production of InP Single-Crystal Body An InP single-crystal body is grown by the VB method. As shown in FIG. 1, two heaters 24a, 24b are used and one inter-heater gap 24abo is provided. Closure plate 25 com-posed of PBN is placed between an InP polycrystal body having a purity of 99.9 mass % and serving as InP source material 13 and B₂O₃ serving as sealing member 23. The closure ratio (percentage of the area of the closure plate with respect to the cross sectional area of the straight body portion of crucible 21 perpendicular to the axial direction) of closure plate 25 is set to 97%. The InP single-crystal body is grown by adjusting a temperature distribution in the crucible to attain a temperature of 1065° C. at a surface of the InP source material and attain a temperature gradient of 2° C./cm at a crystal growth interface in a crystal growth direction.

Production of InP Single-Crystal substrate The outer circumference of the obtained InP single-crystal body was ground and the obtained InP single-crystal body was sliced along a plane perpendicular to the crystal growth direction. Then, the main surface thereof was subjected to mechanical polishing and chemical mechanical polishing (CMP), thereby producing InP single-crystal substrates each having a diameter of 100 mm and a thickness of 525 µm. The oxygen concentration of each of the obtained InP single-crystal substrates is measured by CPAA (Charged Particle Activation Analysis), the thickness of an oxide film formed in the main surface is measured by a spectral ellipsometer (PCA ellipsometer SE-101 provided by Photonic Lattice), and a dislocation density thereof is measured in an optical microscope image (BH₂-UMA provided by Olympus). Fur-ther, emission intensities of oxygen defect centers in the InP crystal substrate are measured by a cathode luminescence measuring device (MonoCL₄ provided by Gatan). Results are collectively shown in Table 1. Here, in the CPAA for the oxygen concentration, 18F is used which is generated by a nuclear reaction between 3He and oxygen, 16O, in the InP crystal body and which undergoes β' decay with a half-life of 109.73 minutes. The InP crystal body having been irradiated with 3He is melted with an acid, and 18F generated by way of a KBF₄ (potassium tetrafluoroborate) precipitation method is chemically sepa-rated. Gamma rays of 511 keV, which are generated by positron annihilation upon the β' decay of 18F, are measured using a NaI detector to determine the number of counts for 10 a specified time after the end of the irradiation by the least squares method. The number of counts after the specified time as determined using a standard sample, SiO2, in the same manner is used for correction, thereby converting it to the oxygen concentration. Moreover, a peak emission intensity (emission wave-length: around 1078 nm) of the oxygen defect centers in the InP crystal substrate is measured at a room temperature (25° C.) with the cathode luminescence (acceleration voltage: kV; electron current: 0.4 nA; beam diameter: 10 nm), whereby an amount of the oxygen defect centers in the InP crystal substrate can be evaluated. When the amount of the oxygen defect centers is smaller than 500 counts/sec, the emission intensity of the oxygen defect centers in the InP crystal substrate is regarded as “Small”. When the amount of the oxygen defect centers is larger than 5000 counts/sec, the emission intensity of the oxygen defect centers in the InP crystal substrate is regarded as “Large”. When the amount of the oxygen defect centers is more than or equal to 500 counts/sec and less than or equal to 5000 counts/sec, the emission intensity of the oxygen defect centers in the InP crystal substrate is regarded as “Appropriate”. When the emission intensity of the oxygen defect centers in the InP crystal substrate is not “Large” and “Small” but is “Appro-priate”, growth from the oxygen defect centers is facilitated during the crystal growth and therefore abnormal defects are less likely to be generated. “Small” is the second most preferable to “Appropriate”. In the case of “Large”, electron mobility in the InP single-crystal body becomes low, thus resulting in decreased characteristics of a device including the InP single-crystal substrate. The invention claimed is:

An indium phosphide single-crystal substrate, wherein: the indium phosphide single-crystal substrate has a CPAA oxygen concentration of more than or equal to 5.5×1015 atoms·cm⁻³ and less than 1×1016 atoms·cm⁻³, the CPAA oxygen concentration being an oxygen concen-tration measured by means of a Charged Particle Acti-vation Analysis (CPAA) that measures oxygen concen-tration using 18F which is generated by a nuclear reaction between 3He and 16O in the indium phosphide single-crystal substrate and which undergoes β+ decay with a half-life of 109.73 minutes; and a diameter of the indium phosphide single-crystal substrate is more than or equal to 100 mm and less than or equal to 150 mm.

Production of InP Single-Crystal Body An InP single-crystal body is grown by the VB method. As shown in FIG. 1, two heaters 24a, 24b are used and one inter-heater gap 24abo is provided. Closure plate 25 com-posed of PBN is placed between an InP polycrystal body having a purity of 99.9 mass % and serving as InP source material 13 and B₂O₃ serving as sealing member 23. The closure ratio (percentage of the area of the closure plate with respect to the cross sectional area of the straight body portion of crucible 21 perpendicular to the axial direction) of closure plate 25 is set to 97%. The InP single-crystal body is grown by adjusting a temperature distribution in the crucible to attain a temperature of 1065° C. at a surface of the InP source material and attain a temperature gradient of 2° C./cm at a crystal growth interface in a crystal growth direction.

Production of InP Single-Crystal substrate The outer circumference of the obtained InP single-crystal body was ground and the obtained InP single-crystal body was sliced along a plane perpendicular to the crystal growth direction. Then, the main surface thereof was subjected to mechanical polishing and chemical mechanical polishing (CMP), thereby producing InP single-crystal substrates each having a diameter of 100 mm and a thickness of 525 µm. The oxygen concentration of each of the obtained InP single-crystal substrates is measured by CPAA (Charged Particle Activation Analysis), the thickness of an oxide film formed in the main surface is measured by a spectral ellipsometer (PCA ellipsometer SE-101 provided by Photonic Lattice), and a dislocation density thereof is measured in an optical microscope image (BH₂-UMA provided by Olympus). Fur-ther, emission intensities of oxygen defect centers in the InP crystal substrate are measured by a cathode luminescence measuring device (MonoCL₄ provided by Gatan). Results are collectively shown in Table 1. Here, in the CPAA for the oxygen concentration, 18F is used which is generated by a nuclear reaction between 3He and oxygen, 16O, in the InP crystal body and which undergoes β' decay with a half-life of 109.73 minutes. The InP crystal body having been irradiated with 3He is melted with an acid, and 18F generated by way of a KBF₄ (potassium tetrafluoroborate) precipitation method is chemically sepa-rated. Gamma rays of 511 keV, which are generated by positron annihilation upon the β' decay of 18F, are measured using a NaI detector to determine the number of counts for 10 a specified time after the end of the irradiation by the least squares method. The number of counts after the specified time as determined using a standard sample, SiO2, in the same manner is used for correction, thereby converting it to the oxygen concentration. Moreover, a peak emission intensity (emission wave-length: around 1078 nm) of the oxygen defect centers in the InP crystal substrate is measured at a room temperature (25° C.) with the cathode luminescence (acceleration voltage: kV; electron current: 0.4 nA; beam diameter: 10 nm), whereby an amount of the oxygen defect centers in the InP crystal substrate can be evaluated. When the amount of the oxygen defect centers is smaller than 500 counts/sec, the emission intensity of the oxygen defect centers in the InP crystal substrate is regarded as “Small”. When the amount of the oxygen defect centers is larger than 5000 counts/sec, the emission intensity of the oxygen defect centers in the InP crystal substrate is regarded as “Large”. When the amount of the oxygen defect centers is more than or equal to 500 counts/sec and less than or equal to 5000 counts/sec, the emission intensity of the oxygen defect centers in the InP crystal substrate is regarded as “Appropriate”. When the emission intensity of the oxygen defect centers in the InP crystal substrate is not “Large” and “Small” but is “Appro-priate”, growth from the oxygen defect centers is facilitated during the crystal growth and therefore abnormal defects are less likely to be generated. “Small” is the second most preferable to “Appropriate”. In the case of “Large”, electron mobility in the InP single-crystal body becomes low, thus resulting in decreased characteristics of a device including the InP single-crystal substrate. The invention claimed is:

An indium phosphide single-crystal substrate, wherein: the indium phosphide single-crystal substrate has a CPAA oxygen concentration of more than or equal to 5.5×1015 atoms·cm⁻³ and less than 1×1016 atoms·cm⁻³, the CPAA oxygen concentration being an oxygen concen-tration measured by means of a Charged Particle Acti-vation Analysis (CPAA) that measures oxygen concen-tration using 18F which is generated by a nuclear reaction between 3He and 16O in the indium phosphide single-crystal substrate and which undergoes β+ decay with a half-life of 109.73 minutes; and a diameter of the indium phosphide single-crystal substrate is more than or equal to 100 mm and less than or equal to 150 mm.

Production of InP Single-Crystal Body An InP single-crystal body is grown by the VB method. As shown in FIG. 1, two heaters 24a, 24b are used and one inter-heater gap 24abo is provided. Closure plate 25 com-posed of PBN is placed between an InP polycrystal body having a purity of 99.9 mass % and serving as InP source material 13 and B₂O₃ serving as sealing member 23. The closure ratio (percentage of the area of the closure plate with respect to the cross sectional area of the straight body portion of crucible 21 perpendicular to the axial direction) of closure plate 25 is set to 97%. The InP single-crystal body is grown by adjusting a temperature distribution in the crucible to attain a temperature of 1065° C. at a surface of the InP source material and attain a temperature gradient of 2° C./cm at a crystal growth interface in a crystal growth direction.

Production of InP Single-Crystal substrate The outer circumference of the obtained InP single-crystal body was ground and the obtained InP single-crystal body was sliced along a plane perpendicular to the crystal growth direction. Then, the main surface thereof was subjected to mechanical polishing and chemical mechanical polishing (CMP), thereby producing InP single-crystal substrates each having a diameter of 100 mm and a thickness of 525 µm. The oxygen concentration of each of the obtained InP single-crystal substrates is measured by CPAA (Charged Particle Activation Analysis), the thickness of an oxide film formed in the main surface is measured by a spectral ellipsometer (PCA ellipsometer SE-101 provided by Photonic Lattice), and a dislocation density thereof is measured in an optical microscope image (BH₂-UMA provided by Olympus). Fur-ther, emission intensities of oxygen defect centers in the InP crystal substrate are measured by a cathode luminescence measuring device (MonoCL₄ provided by Gatan). Results are collectively shown in Table 1. Here, in the CPAA for the oxygen concentration, 18F is used which is generated by a nuclear reaction between 3He and oxygen, 16O, in the InP crystal body and which undergoes β' decay with a half-life of 109.73 minutes. The InP crystal body having been irradiated with 3He is melted with an acid, and 18F generated by way of a KBF₄ (potassium tetrafluoroborate) precipitation method is chemically sepa-rated. Gamma rays of 511 keV, which are generated by positron annihilation upon the β' decay of 18F, are measured using a NaI detector to determine the number of counts for 10 a specified time after the end of the irradiation by the least squares method. The number of counts after the specified time as determined using a standard sample, SiO2, in the same manner is used for correction, thereby converting it to the oxygen concentration. Moreover, a peak emission intensity (emission wave-length: around 1078 nm) of the oxygen defect centers in the InP crystal substrate is measured at a room temperature (25° C.) with the cathode luminescence (acceleration voltage: kV; electron current: 0.4 nA; beam diameter: 10 nm), whereby an amount of the oxygen defect centers in the InP crystal substrate can be evaluated. When the amount of the oxygen defect centers is smaller than 500 counts/sec, the emission intensity of the oxygen defect centers in the InP crystal substrate is regarded as “Small”. When the amount of the oxygen defect centers is larger than 5000 counts/sec, the emission intensity of the oxygen defect centers in the InP crystal substrate is regarded as “Large”. When the amount of the oxygen defect centers is more than or equal to 500 counts/sec and less than or equal to 5000 counts/sec, the emission intensity of the oxygen defect centers in the InP crystal substrate is regarded as “Appropriate”. When the emission intensity of the oxygen defect centers in the InP crystal substrate is not “Large” and “Small” but is “Appro-priate”, growth from the oxygen defect centers is facilitated during the crystal growth and therefore abnormal defects are less likely to be generated. “Small” is the second most preferable to “Appropriate”. In the case of “Large”, electron mobility in the InP single-crystal body becomes low, thus resulting in decreased characteristics of a device including the InP single-crystal substrate. The invention claimed is:

An indium phosphide single-crystal substrate, wherein: the indium phosphide single-crystal substrate has a CPAA oxygen concentration of more than or equal to 5.5×1015 atoms·cm⁻³ and less than 1×1016 atoms·cm⁻³, the CPAA oxygen concentration being an oxygen concen-tration measured by means of a Charged Particle Acti-vation Analysis (CPAA) that measures oxygen concen-tration using 18F which is generated by a nuclear reaction between 3He and 16O in the indium phosphide single-crystal substrate and which undergoes β+ decay with a half-life of 109.73 minutes; and a diameter of the indium phosphide single-crystal substrate is more than or equal to 100 mm and less than or equal to 150 mm.