| 摘要 |
PURPOSE:To reduce the misfit of crystal lattices between both magnesia-spinel layer and a semiconductor layer, and to obtain a wafer with the excellent semiconductor layer having few crystal defects by superposing the magnesia-spinel layer and the semiconductor layer on a magnesia substrate in succesion. CONSTITUTION:MgCl2 in a boat 14A at an upper step of a chamber 13 in a reaction tube 11 is heated 18B and gasified, and forwarded on mangnesia wafers 16 by H2 introduced 12A. Al in a boat 14B at a lower step is heated 18A, and AlCl2 is manufactured by HCl fed in together with H2 and forwarded onto the wafers 16. Magnesia- spinel is grown on the wafers 16 heated 18C through a predetermined reaction. Magnesia-spinel having excellent crystallizability is grown within a range of a growth temperature of 750<=T<=1,200 deg.C, the concentration ratio of MgCl2 to AlCl2 of 0.05<= R<=10 and a growth rate of 0.002<=SG<=0.5mum/min, and a lattice constant extends over 7.9-8.15Angstrom . When Si, GaAs, etc. are grown on the wafer, crystal defects are reduced, and electrical characteristics are also improved. Accordingly, when the wafer is used, elements can be isolated completely, and floating capacitance between the wafer and a substrate is also reduced. |
