Abstract: Doped thin films of GaAs are chemically vapor deposited by depositing a high resistant buffer layer of GaAs on a GaAs substrate by gaseous reaction of a mixture of arsine gas and trimethylgallium in the gas phase over the substrate while the temperature of the substrate is maintained within the range of 600.degree.-700.degree. C., stopping the supply of trimethylgallium to the gas mixture undergoing reaction and increasing the temperature of the substrate to within the range of 700.degree.-800.degree. C., and then resuming the supply of trimethylgallium to and supplying hydrogen sulfide to the gas phase over the substrate at the stated temperature, thereby depositing a doped GaAs layer over the buffer layer on the substrate having a distribution of carrier density of less than 5%.

Abstract: A method and an apparatus for growing a crystal of a compound semiconductor, in which a heater, used to heat a boat for growing the semiconductor crystal, is disposed around an ampule containing the boat, and a melt of the compound semiconductor, which is prepared in the boat, is freezed gradually at a predetermined temperature gradient including the freezing point of the melt, from a crystal growth starting end of the boat to a crystal growth terminating end thereof, whereby a single crystal or a polycrystal is grown. At the start of crystal growth, a crystalline nucleus is formed by periodically changing the temperature of the crystal growth starting end of the boat, in descending and ascending modes, within a temperature range lower than the melting point of the compound semiconductor, after once lowering the temperature of the starting end to a level lower than the melting point by means of a heater block opposed to the starting end.

Abstract: A vapor phase deposition method for the GaAs thin film is disclosed, which is characterized in that, in the metal organic chemical vapor deposition method (MOCVD method) wherein arsine gas and organic gallium gas are decomposed thermally and GaAs crystals are allowed to deposit onto the GaAs substrate, for the deposition of n-type conductive GaAs crystals, arsine gas and organic gallium gas are supplied at such a supplying ratio (V/III) as p-type conductive GaAs crystals are deposited unless an impurity is added intentionally and gas of the compounds of VI group elements is added to these gases to make n-type conductive GaAs crystals having a carrier density of not less than 1.times.10.sup.16 cm.sup.-3.

Abstract: A chemical vapor deposition method for making a semiconductor thin film is disclosed, which is characterized in that, in the method wherein semiconductor thin films are allowed to deposit onto the substrates by allowing the susceptor in the shape of polygonal frustum fitted with a plurality of semicondutor substrates to the side faces thereof to rotate in the vertical type reaction tube, by introducing the source gases and the carrier gas into the tube, and by heating the substrates to allow the source gases to react through thermal decomposition, the number of rotations of susceptor is varied in terms of rectangular wave function, trapezoidal wave function or sine wave function and the susceptor is allowed to rotate in converse directions depending on the positive region and the negative region of the function.