Ternary substrates grown for singlequantumwell lasers

A research team at Fujitsu Laboratories (Atsugi, Japan) have developed liquidencapsulatedCzochralski techniques to grow ternary InGaAs crystals with a quality that allows subsequent growth of singlequantumwell InGaAs¥laser diodes. Bulk crystal compositional uniformity was improved by ensuring melt refreshment during growth, which was achieved by supplying the GaAs source material at a constant temperature. Ingots of 1.5 and 6 cm lengths were grown with mobilities (5000 cm2/V s) comparable to undoped GaAs. Devices emitted at 1.03 µm and had a threshold current density of 222 A/cm2 and characteristic temperature of 221 K. This structure may circumvent the inferior temperature characteristics of devices made on In¥substrates.