Electron mobility enhancement in epitaxial multilayer Si-Si1−xGex alloy films on (100) Si

Abstract
Enhanced Hall‐effect mobilities have been measured in epitaxial (100)‐oriented multilayer n‐type Si/Si1−xGex films grown on single‐crystal Si substrates by chemical vapor deposition. Mobilities from ∼20 to 40% higher than that of epitaxial Si layers and ∼100% higher than that of epitaxial SiGe layers on Si were measured for the doping range ∼8×1015–∼1017 cm−3. The mobilities of multilayer Si/SiGe films approach that of single‐crystal Si films at ∼2×1017 cm−3. No mobility enhancement was observed in multilayer p‐type (100) films and n‐type (111)‐oriented films. Experimental studies included the effects upon film properties of layer composition, total film thickness, doping concentrations, layer thicknesses, and growth temperature.