Rapid P-injection in-situ synthesis and growth large diameter LEC InP single crystal

High purity InP is necessary for the preparation of high quality InP single crystal especially low Fe content semi-insulating and annealed undoped semi-insulating InP single crystal. In-situ phosphorus injection synthesis of InP has several advantages over the two-step process of compounding and growing in separate furnace. In 1982 it was reported by our group that around 500g InP was synthesized and semi-insulating InP single crystals grown in one step in 30-60 minutes. A large high pressure puller have been set up, which can be used to synthesize and grow large diameter InP single crystal in our laboratory. Now 3400g InP can be synthesized reproducible and single crystals can be grown in the puller. The red phosphorus used for synthesis is contained in two vessels, which can be manipulated separately during the synthesis process. The two phosphorus vessels are heated by the auxiliary heater and the phosphorus vapour is injected into the indium melt in the crucible. We have developed a process for the rapid synthesis of InP. The whole synthesis process only needs 60-70 minutes. The synthesized InP could be indium-rich, stoichiometric or phosphorus-rich which depend on the quantity of excess phosphorus and other conditions such as the temperature of indium melt in the crucible, the thermal field, phosphorus injection speed etc. After the synthesis, InP crystal can be pulled by the conventional LEC method. Twin-free 3-inch and 4-inch <100> InP single crystal can be obtained. The InP single crystal wafer is cut from the ingot for the measurement of electronic parameters. The carrier concentration of P-injection in-situ synthesis InP at T = 300 K is n = 2 × 10¹⁵ - 10¹⁶ cm^-3, the mobility is 3500 4900 cm²/Vs. These depend on the raw materials used. At T = 77 K the best result n = 2.36 × 10¹⁵ cm^-3, the mobility is 4.8 × 10⁴ cm²/Vs. This kind of InP can be made semi-insulating with high temperature annealing or low iron doping levels.