NOVELTY - Making an oligosilane or polysilane comprises (a) combining one or more silane compounds (I) with a catalyst comprising N-heterocyclic carbene, N-heterocyclic silylene, N-heterocyclic germylene, N-heterocyclic carbene-metal complex, N-heterocyclic silylene-metal complex, N-heterocyclic germylene-metal complex, lanthanide metal catalyst, and/or their supported versions to form the oligosilane or polysilane, and (b) removing the catalyst from the oligosilane or polysilane.    USE - The oligosilane or polysilane is useful in an ink composition, which is useful for forming a semiconductor film (i.e. a group IVA semiconductor film), which is useful in a thin film transistor, capacitor, diode, resistor, circuit, radio frequency identification tag, display backplane, sensor and photovoltaic device (all claimed). The oligosilane or polysilane is useful as a precursor for making silicon thin films and semiconductor devices, where the devices and films are useful in displays (including flat panel, plasma, LCD, and organic or inorganic LED), radio frequency devices, electronic article surveillance devices, sensors, microelectromechanical systems and solar device.    ADVANTAGE - The method provides oligosilane or polysilane with low levels of carbon and metal contaminants, low volatility, and high molecular weight, purity, solubility, stability, viscosity and yield in a less time-consuming and cost-effective manner. The oligosilane or polysilane provides thin semiconductor film with accurate thickness control, good surface smoothness, consistent density and/or good pattern fidelity.    DETAILED DESCRIPTION - Making an oligosilane or polysilane comprises (a) combining one or more silane compounds of formula (AnHjRk) (I) with a catalyst comprising N-heterocyclic carbene, N-heterocyclic silylene, N-heterocyclic germylene, N-heterocyclic carbene-metal complex, N-heterocyclic silylene-metal complex, N-heterocyclic germylene-metal complex, lanthanide metal catalyst, and/or their supported versions to form the oligosilane or polysilane, and (b) removing the catalyst from the oligosilane or polysilane.    A = Si or Ge;    n = at least 1;    j = at least 2, where the sum of j and k is n+1 to 2n+2, when n is odd, and the sum of j and k is n to 2n+2, when n is even; and    R = aryl, halo or pseudohalide.    INDEPENDENT CLAIMS are included for:    (1) an ink composition comprising the oligosilane or polysilane, and a solvent in which the oligosilane or poly silane is soluble;    (2) forming a semiconductor film from the ink composition comprising (a1) coating or printing the ink composition onto a substrate, where the ink composition comprises a solvent and a N-heterocyclic compound of formulae (NHC)2(A2) (II), (NHC)2(HxD1A) (III), (NHS)2(A2) (IV), (NHS)2(HxD1A) (V), (NHS)2(HxD12) (VI) and/or (NHC)2(HxD12) (VII), (b1) heating the coated or printed ink composition to form an amorphous, hydrogenated semiconductor, and (c) optionally, annealing and/or irradiating the amorphous, hydrogenated semiconductor to at least partially crystallize and/or reduce a hydrogen content of the amorphous, hydrogenated semiconductor; and    (3) making a thin film transistor, capacitor, diode and/or resistor, comprising forming the semiconductor film by the above method of forming a semiconductor film, and forming one or more conductive and/or insulating films in physical proximity to the semiconductor film.    NHC = N-heterocyclic carbene;    NHS = N-heterocyclic silylene;    D1 = P, As, Sb or B; and    x = 0 unless D1 is B, where x is equal to the number of D1 atoms in (II)-(VII).