Physical mechanism of secondary electron emission in Si wafers

CMOS compatible RF/microwave devices such as filters and amplifiers, have been widely used in wireless communication systems. However, it often exists on secondary electron emission phenomenon among those RF/microwave devices based o silicon (Si) wafers, especially in high-frequency range. In this paper, we have studied the major factors that influence the secondary electron yield (SEY) in commercial Si wafers with different doping concentrations. It shows that SEY is suppressed as the increase of doping concentrations, corresponding to a relatively short effective escape depth λ. Meanwhile, the reduced narrow band gap is beneficial to suppress the SEY by through the first-principles calculations, in which the absence of shallow energy band below the conduction band would easily capture electrons. Thus, the new physical mechanism combined the effective escape depth and band gap, would provide useful guidance for the design of integrated RF/microwave devices based on Si wafers.