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The electrical properties of In 0.53 Ga 0.47 As grown on full two-inch InP wafers have been studied. Special emphasis was placed on investigations of the vertical and lateral uniformity of the material quality. Using the Mobility Spectrum Technique, a way of unambiguously analyzing Hall effect data from samples with multiple conduction paths, a conducting substrate-epi interface layer was found in some In 0.53 G 0.47 As films. Despite the presence of the interface layer, good, vertically uniform mobilities in n-doped samples were still measured in the film. A large-scale lateral nonuniformity in the sheet resistance was associated with variations in the interface layer. A 1.5 μm thick undoped In 0.52 Ga 0.47 As layer with an In 0.52 Al 0.48 As buffer layer exhibited a 77K mobility of 65,100 cm 2 /V⋯s with no sign of interface conduction. Some lateral nonuniformity in the sheet resistance similar to the doped sample was still observed, indicating that the substrate surface quality still affects the film quality to some degree. However, the lateral variations in films with AlInAs buffers are much smaller and are not expected to affect, e.g., modulation-doped structures. |
