| 摘要 |
PURPOSE:To prevent an abnormal increase in the vicinity of the surface of impurity concentration in vapor phase epitaxy by supplying and stopping gases for epitaxial growth and doping at the same time and supplying and stopping a gas lowering impurity concentration at the time later than the supply and stopping of said gases. CONSTITUTION:Bubblers 1, 1' are kept at a temperature such as 25 deg.C, and H2 gas is flowed to an A supply system for epitaxial growth at the rate of 300cc/min, H2 gas to a B system lowering impurity concentration at the rate of 1.0l/min and H2 gas to a C system for doping at the rate of 1,000ppm. A Ga source is kept at 800-850 deg.C and a compound semiconductor wafer 3 at 700-750 deg.C. Valves in the A and C systems are closed at the time T3, the supply of gases is stopped, and a valve in the B system is closed at the time later than the stopping of the supply of the gases by 5 or 10sec. Carrier concentration in an epitaxial film is equalized in a vapor phase epitaxial layer shaped in this manner, thus preventing the abnormal increase of carrier concentration in the vicinity of the surface.
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