Thermal annealing of modulation-doped Si/SiGe heterostructures with high electron mobilities

Abstract

We grew n-type modulation-doped Si/SiGe multiple quantum well structures with the highest electron mobilities reported so far for this heterosystem. The samples were annealed at temperatures between 750 and 950 °C for 1000 s and subsequently characterized by their Hall mobilities and carrier concentrations. Only a moderate decrease in room-temperature mobility is observed up to annealing temperatures of 900 °C. At 950 °C the samples turn more or less into homogeneously doped SiGe alloys. The annealing effects are discussed in terms of dopant and Ge diffusion, and of metastability of the SiGe layers.