Apparatus for growing GaAs single crystal by using floating zone

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will hereunder be described with respect to the preferred embodiments by referring to the accompanying drawings.
FIG.
1 shows an embodiment of the GaAs single crystal growing apparatus which relies on the floating zone method according to the present invention.
Reference numeral 1 represents a quartz cylinder; 3 a GaAs seed crystal; 4 a GaAs single crystal rod; 5 a GaAs melt region; 6 a GaAs polycrystal rod; 8 a supporting rod for the GaAs polycrystal rod 6; 7 a chuck for establishing a connection of the GaAs polycrystal 6 with the supporting rod 8; 9 a connector for the GaAs seed crystal 3 and its supporting rod 10; 11 a quartz vessel for containing As; 12 a narrow quartz tube for connecting the As vessel 11 with the quartz cylinder 1 of the apparatus for communication therebetween; 13 an As element of a high purity; 14 and 15 stainless plates for sealingly supporting an open end of the quartz cylinder 1, respectively; 16 and 17 sealing members made of, for example, O-rings or gaskets, respectively; 20 a working coil serving as a radio frequency (hereinafter to be referred to as RF) induction heater for heating the GaAs polycrystal 6 to form its melt 5; 21 a power supply using, for example, RF oscillator; 22 a working coil serving as an RF induction heater to heat As 13; 23 a power supply of a high frequency such as, similar to 21, an RF oscillator; 24 a thermometer such as a pyrometer for measuring the temperature of the melt region 5; 26 a thermometer such as a pyrometer for controlling the vapor pressure of As 13; 25 and 27 temperature controllers for controlling the RF power supplies 21 and 23, respectively; and 28 a window for observing the temperature.
As stated above, the crystal growth according to the present invention is performed by relying on the floating zone method.
To begin with, the polycrystal located at the bottom end of the polycrystal rod 6 is heated by the induction heater to the melting point of GaAs or somewhat higher than that to about 1240