Evaluation of 4” InP Substrates for Epi-Ready Production MBE Growth
Fastewnau, *W.K. Liu, D. Lubyshev, X.-M Fang, Y. Wu, C. Doss
4-inch diameter semi-insulating InP substrates from multiple suppliers were evaluated and compared in terms of their epi-readiness as required for production molecular beam expitaxy. All epiwafers in this work exhibited excellent crystalline and structural properties, and the electrical properties were consistent from vendor-to-vendor. The post-growth surface morphology and defect density were typically within standard expectations; however, occasionally some fallout was observed due to variations in substrate surface finish, unrelated to the epi-growth. Significant differences in epilayer-substrate interfacial properties were observed between the various vendors and also within substrate lots from individual vendors. While some substrates exhibited a clean interface, others had n-type charge accumulations of varying magnitudes. The interface contamination, silicon or sulfur arising from the substrate surface preparation process or from the substrate packaging, can lead to poor device isolation.
Keywords: InP Substrates, MBE, Surface Morphology, Interfacial Contamination