Deposition of semiconductor materials by liq. phase epitaxy - where melt is initially heated above deposition temp.

摘要

The substrate is dipped vertically into a crucible contg. a melt satd. with >=2 constituents. The melt contains 1.5 times the required amt. of the constituents, in small pieces, and is held above the deposition temp. (Td) until equilibrium is achieved. The temp. is then lowered to Td, and a jig contg. >=2 substrates dipped into the melt while some crystallisation occurs due to the drop in temp.; the jib is designed to displace any solid materials floating on the melt. The melt is pref. held initially for 2 hr at 50 degrees C above Td, the substrates being held 15 cm above the crucible during this period; and the substrates are pref. sepd. by 3-4 mm in the jig. Prior to deposition, the reverse side of the substrates is pref. passivated by a layer of SiO2; Si3N4; or sputtered Al2O3. The jig is pref. made of quartz and/or graphite, and uses springs to locate the substrates in the jig. Used in the mfr. of light emitting diodes, photo-cathodes or other optoelectronic elements, by depositing materials such as GaP, GaAs, Ga1-xAlxAs.