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This paper compares the properties of silicon oxide and nitride as host matrices for Er ions. Erbium-doped silicon nitride films were deposited by a plasma-enhanced chemical-vapour deposition system. After deposition, the films were implanted with Er3+ at different doses. Er-doped thermal grown silicon oxide films were prepared at the same time as references. Photoluminescence features of Er3+ were inspected systematically. It is found that silicon nitride films are suitable for high concentration doping and the thermal quenching effect is not severe. However, a very high annealing temperature up to 1200 degC is needed to optically activate Er3+, which may be the main obstacle to impede the application of Er-doped silicon nitride. [ABSTRACT FROM AUTHOR]

Graphene is a new promising candidate for application in radio-frequency (RF) electronics due to its excellent electronic properties such as ultrahigh carrier mobility, large threshold current density, and high saturation velocity. Recently, much progress has been made in the graphene-based RF field-effect transistors (RF-FETs). Here we present for the first time the high-performance top-gated RF transistors using millimeter-scale single graphene domain on a SiO2/Si substrate through a conventional microfabrication process. A maximum cut-off frequency of 178 GHz and a peak maximum oscillation frequency of 35 GHz are achieved in the graphene-domain-based FET with a gate length of 50 nm and 150 nm, respectively. This work shows that the millimeter-scale single graphene domain has great potential applications in RF devices and circuits. [ABSTRACT FROM AUTHOR]