Nondestructive measurement of resistivity in bulk InxGa1−xAs crystals

By using a nondestructive resistivity measurement (NDRM) technique, which is based on a Fourier analysis of charge response in a metal–insulator–semiconductor–metal (MISM) structure, the resistivity in bulk InxGa1−xAs crystals has been measured. Two-dimensional (2-D) distribution map measured in a sample sliced along the growth direction in a graded composition ingot of InxGa1−xAs crystal showed that the resistivity gradually decreased from 108 to 105 Ω cm with the increase of indium composition except in the seeding region. It was also found that there were inhomogeneous distributions of resistivity in the seeding region due to the diffusion of Si from the GaAs seed crsytal. Since the inhomogeneous distribution of resistivity reflects the growth conditions such as temperature distribution and melt flow, the nondestructive measurement of resistivity by the NDRM technique is useful for evaluating not only the crystal quality but also the growth technique in bulk InxGa1−xAs crystals.