NOVELTY - Method of preparing an improved FET, which has a source region (i), a drain region (ii), a channel layer (iii), a gate region (iv), and an electrically insulating layer (v), comprises: preparing (iii), which comprises a film of a metal chalcogenide semiconducting material, by preparing a solution of a precursor of the metal chalcogenide by adding an elemental metal and an elemental chalcogen to a hydrazine compound; applying precursor solution onto a substrate to produce precursor film; and annealing the film at 150-350 degrees C to produce the metal chalcogenide film on the substrate.    USE - The method is useful for preparing FET, photovoltaic device and phase-change memory device (all claimed) for electronic applications e.g. optical rewritable memory, solar cell, LED and thin film transistor.    ADVANTAGE - The method replaces the metal chalcogenide, used in current techniques, with corresponding elemental metal and the combination of the elemental metal with chalcogen makes the elemental metal to directly dissolve in hydrazine-type solvent at room temperature. The method provides a high throughput/low-temperature solution-based deposition of high quality metal chalcogenide films on the various electronic applications. The method uses elemental metals and not metal salts thus avoiding the introduction of impurities.    DETAILED DESCRIPTION - Method of preparing an improved FET of the type having a source region (i), a drain region (ii), a channel layer (iii), including a semiconducting material, extending between (i) and (ii), a gate region (iv), disposed in spaced adjacency to the channel layer, and an electrically insulating layer (v) between (iv) and (i)-(iii), comprises: preparing the channel layer, comprising a film of a metal chalcogenide semiconducting material, which comprises preparing a solution of a precursor of a metal chalcogenide by adding an elemental metal and an elemental chalcogen to a hydrazine compound to provide a solution of the precursor of the metal chalcogenide; applying the solution of the precursor onto a substrate to produce a film of the precursor; and annealing the film of the precursor to produce the metal chalcogenide film on the substrate, where the annealing is carried out at 150-350 degrees C. INDEPENDENT CLAIMS are included for:    (1) FET prepared by the method;    (2) a method-2 of preparing a photovoltaic device or a phase-change memory device comprising preparing a film by depositing a film of a metal chalcogenide or a layer by depositing a layer of the metal chalcogenide, respectively, where the method-2 comprises preparing the solution of hydrazine-based precursor of the metal chalcogenide that comprises adding the elemental metal and the elemental chalcogen to hydrazine compound to provide the solution of the precursor of the metal chalcogenide; applying the solution of the precursor onto a substrate to produce a film of the precursor; and annealing the film of the precursor to produce the metal chalcogenide film on the substrate; and    (3) the photovoltaic device or a phase-change memory device prepared by the method-2.    DESCRIPTION OF DRAWING(S) - The diagram shows a schematic representation of thin-film transistor with spin-coated tin sulfide channel.