Growth of high-purity semi-insulating bulk GaAs for integrated-circuit applications

Growth of high-purity bulk semi-insulating GaAs by the Liquid-Encapsulated Czochralski (LEC) method has produced thermally stable, high-resistivity crystals suitable for use in direct ion implantation. Large round substrates have become available for integrated-circuit processing. The implanted wafers have excellent electrical uniformity (±4 percent V
p
) and have shown electron mobility as high as 4800cm
²
/V.s for Se implants with 1.7 × 10
¹⁷
cm
^-3
peak doping. Careful control of background doping through in situ synthesis has produced GaAs with Si concentrations as low as 6 × 10
¹⁴
cm
^-3
grown from SiO
2
crucibles. Detailed results of qualification tests for ion implantation in LEC GaAs will be discussed. Feasibility of successful high-speed GaAs large-scale integrated circuits using LEC substrates will be described.