Smoothness of etched facets at all angles is a critical requirement for photonic devices in such materials as AlGaAs/GaAs which are etched at variable angles by directed ion beam/reactive gas etching systems such as chemically assisted ion beam etching (CAIBE). Semimetallic amorphous carbon thin films have been found to produce excellent etched facets that are smoother than those etched with other mask materials. This material also exhibits very low CAIBE etch rates and very low chemical reactivity with substrate materials such as AlGaAs/GaAs or silicon. The semimetallic amorphous carbon was deposited up to 400 nm thick by electron beam sublimation of graphitic carbon onto substrates such as polished wafers of GaAs, Si, Ge, and onto glass. The electron-beam sublimation deposited (EBSD) semimetallic amorphous carbon, EBSD semimetallic a-C, can be patterned directly by SF6 reactive ion etcher via a standard photoresist mask, it can be used as an etch mask in CAIBE systems, and it can be stripped clean in hydrogen or oxygen plasmas. Etch rate selectivities of approximately 30:1 of (AlGaAs):(EBSD semimetallic a-C) were observed in CAIBE experiments. The EBSD semimetallic a-C is being used as the etch mask in a self-aligned four-CAIBE steps process to microfabricate surface-emitting high-power single-mode AlGaAs/GaAs laser arrays.