[0038] Embodiment 2
[0039] The present embodiment is characterized in that, with reference to FIGS. 1 and 3 , carbon in the graphite crucible (crystal growth vessel 12 ) forming the inner wall of the carbon-containing gas production chamber 23 and by metal oxide placed in the carbon-containing gas production chamber 23 3 CO gas and/or CO generated by the reaction between the generated metal oxide gases 2 , is supplied to the inside of the crystal growth chamber 24 as a carbon-containing gas.
[0040] In this embodiment, referring to FIG. 3 , as in Embodiment 1, a crystal growth chamber 24 having a high temperature resistant material 21 as a wall, and a carbon-containing gas production chamber having a high temperature resistant material 21 and a crystal growth vessel 12 as walls 23. Formed in the crystal growth vessel 12 (graphite crucible). Here, air circulates through the crystal growth chamber 24 and the carbon-containing gas production chamber 23 via the opening portion 21h, and circulates through the outside of the carbon-containing gas production chamber 23 and the crystal growth vessel 12 via the opening portions 12h, 13a, 13b. Here, for ventilation, the crystal growth chamber 24 communicates with the carbon-containing gas production chamber 23 via the opening portion 21h, and for ventilation, the carbon-containing gas production chamber 23 communicates with the outside of the crystal growth vessel 12 via the opening portions 12h, 13a, and 13b .
[0041] This embodiment mode is similar to Embodiment Mode 1 in that with reference to FIGS. 1 and 3 , the AlN source 1 is placed at one end of the crystal growth chamber 24 where the opening portion 21h exists, and the seed substrate 2 is placed at the opposite side of the crystal growth chamber 24. There is an end opposite to one end of the opening portion 21 h ; and this embodiment is different from Embodiment 1 in that the metal oxide 3 is further placed in the carbon-containing gas production chamber 23 . Here, the metal oxide is not particularly limited as long as it reacts with carbon to generate CO gas and/or CO 2 Metal oxides of gases, but produced from CO gas and/or CO 2 gas without adversely affecting the crystallinity of AlN crystals, Al 2 O 3 is a preferred example of the metal oxide.
[0042] While nitrogen gas is supplied as a carrier gas to the reaction chamber 11 (outside of the crystal growth vessel 12 in FIG. 3), the crystal growth vessel 12, the carbon-containing gas production chamber 23 and the crystal growth chamber 24 are heated, as a result, at a high temperature (eg, , a temperature of about 1700° C. to 2300° C.) atmosphere, the metal oxide gas is generated from the metal oxide 3 placed in the carbon-containing gas production chamber 23 . This metal oxide gas reacts with carbon in the graphite of the crystal growth vessel 12 (graphite crucible) forming the inner wall 12s of the carbon-containing gas production chamber 23 to generate CO gas and/or CO 2 gas as carbon-containing gas. and N entering the crystal growth vessel 12 from the outside of the crystal growth vessel 12 via the opening portions 13a, 13b and 12h 2 (nitrogen) gas together, CO gas and/or CO 2 The gas is supplied to the crystal growth chamber 24 via the opening portion 21h. In this way the CO gas and/or CO 2 The gas is supplied to the inside of the crystal growth chamber 24 so that CO gas and/or CO in the crystal growth chamber 24 during AlN crystal growth 2 The gas reaches a predetermined amount or more. In addition, changing the diameter of the opening portion 21h can increase and decrease the CO gas and/or CO supplied to the inside of the crystal growth chamber 24 2 amount of gas. That is, lengthening the diameter of the opening portion 21h increases the supply of CO gas and/or CO to the inside of the crystal growth chamber 24 2 amount of gas.
[0043] In the crystal growth chamber 24 , the sublimation of the AlN material 1 produces a source of AlN gas, and the solidification of the AlN gas source results in the growth of AlN crystals 4 on the seed substrate 2 . In this crystal growth, the CO gas and/or CO supplied to the inside of the crystal growth chamber 24 2 The gas eliminates crystal non-growth regions (not shown) on the seed substrate 2 , and AlN crystals 4 grow across the front side of the seed substrate 2 . As a result, large-diameter-span AlN crystals with good crystallinity can be obtained.