Optical and Electrical Characterization of Melt-Grown Bulk Ternary In$_{x}$Ga$_{1-x}$As*

Recent crystal growth technology breakthroughs led to successful growth of good quality bulk melt-grown ternary In$_{x}$Ga$_{1-x}$As single crystals. However, these bulk materials have not been well investigated compared to the epitaxial layers grown on a binary compound semiconductor, GaAs. Therefore, the optical and electrical properties of the bulk grown In$_{x}$Ga$_{1-x}$As have been investigated systematically as a function of temperature and In mole fraction x. The results show that the refractive index increases linearly with temperature from 100 to 300 K and also with In composition x from 0.0 to 0.9 for several IR wavelengths. Typical refractive index values are 3.388 and 3.376 for 4.6 and 10.6 $\mu $m, respectively, at 300 K for x=0.5. The results of Hall-effect measurements show that the electron concentrations increase monotonically with x, while the mobilities decrease as x increases from 0.5 to 1.0. Typical electron concentration and mobility at 300 K are 1.3x10$^{16}$/cm$^{3}$ and 9.1x10$^{3}$cm$^{2}$/V S, respectively, at x=0.75.