Complementary metal-oxide semiconductor-compatible detector materials with enhanced 1550 nm responsivity via Sn-doping of Ge/Si(100)

Previously developed methods used to grow Ge_{1- y}Sn_y alloys on Si are extended to Sn concentrations in the 10¹⁹-10²⁰cm^-3 range. These concentrations are shown to be sufficient to engineer large increases in the responsivity of detectors operating at 1550 nm. The dopant levels of Sn are incorporated at temperatures in the 370-390 C range, yielding atomically smooth layers devoid of threading defects at high growth rates of 15-30 nm/min. These conditions are far more compatible with complementary metal-oxide semiconductor processing than the high growth and processing temperatures required to achieve the same responsivity via tensile strain in pure Ge on Si. A detailed study of a detector based on a Sn-doped Ge layer with 0.25 (1.1 10²⁰cm^-3) Sn range demonstrates the responsivity enhancement and shows much better I-V characteristics than previously fabricated detectors based on Ge _1-ySn_y alloys with y 0.02.