| 摘要 |
1514126 Liquid phase epitaxial growth MATSUSHITA ELECTRIC INDUSTRIAL CO Ltd 20 April 1976 [17 April 1975 9 May 1975] 15878/76 Heading BIS An epitaxial layer of a Group III-V semiconductor is deposited on a crystal substrate from a metal melt by preparing a saturated solution of the semiconductor which is free from precipitate at a predetermined temperature, cooling to a second temperature in isolation from any semiconductor source to give a supercooled solution, contacting the substrate with the solution, cooling until the required layer thickness is reached, separating the substrate from the solution, and cooling the substrate at a quicker rate. The second temperature is 0.5-5�C below the initial predetermined temperature. The saturated solution is formed by preparing an unsaturated solution (e.g. at 5-10% below saturation) at the predetermined temperature, and contacting it with a supplementary source of the semiconductor. The solution may be used repeatedly after reheating. The semiconductor may be GaAs, GaP, InP, InAs, GaSb, InSb or Ga 1-x Al x As. Dopants may be used e.g. Sn, Si, Te or Se for n-type layers, or Zn, Ge or Si for p-type layers. The GaAs source material may be doped with Cr, Mn or NH 3 . The metal melt may be Ga. The substrate crystal may be a 20 x 20 x 3mm GaAs crystal doped with Cr, and may have an off-angle of up to 15� from the [100] plane. Suitable apparatus comprises a lower boat 14 having two recesses 18, 24 for the substrate crystal 20 and supplementary source 24, and an upper boat 16 slidable thereon and having a reservoir 26 for the melt 28. Semiconductor material 30 is dissolved in the melt which is then contacted with the source 24 until saturated (C), returned to (B) for cooling, and then contacted with substrate 20 (D). The assembly may be located in an electric furnace in a stream of hydrogen, and may comprise an array of 6-30 boats in a stack. For removing the substrate the recess 20 may terminate at a side surface of boat 14 or may be formed as a removable cassette. Up to three recesses 18, 22 may be formed in the boat 14 either in line or symmetrically about the reservoir 32 (see Figs. 6-15 - not shown). |
