NOVELTY - Method for forming particles, comprises: either decomposing at least one single source precursor in the presence of at least one thiol, and forming the particles from one or more decomposition products of the single source precursor; or reacting at least one single source precursor with a thiol to form a pre-copolymer of the single source precursor, decomposing the pre-copolymer of the single source precursor, and forming the particles from one or more decomposition products of the pre-copolymer of the single source precursor.    USE - The method is useful for forming particles of I-III-VI2 material in a wurtzite phase and/or chalcopyrite phase, forming a semiconductor material, and forming a semiconductor device including thin-film solar cells (all claimed), a diode including a light emitting diode, a radiation sensor, solid state laser devices, or vertical cavity surface emitting lasers.    ADVANTAGE - The method minimizes defects, and fabrication costs.    DETAILED DESCRIPTION - INDEPENDENT CLAIMS are included for:    (1) a device fabricated using the method;    (2) method-1 of forming a semiconductor material comprising forming particles comprising a I-III-VI2 material in a wurtzite phase, combining the particles with a carrier to form a particle matrix, depositing the particle matrix over at least a portion of a substrate, and annealing the particles to convert the I-III-VI2 material in the wurtzite phase to a chalcopyrite phase, where I represents an element in group I comprising group IA and group IB of the periodic table, III represents an element in group III comprising group IIIB and group IIIA of the periodic table, and VI represents an element in group VI comprising group VIB and group VIA of the periodic table;    (3) method-2 of forming a semiconductor device comprising either forming particles of a I-III-VI2 material in a wurtzite phase over a first conductive material overlying a substrate, performing an annealing process to convert the particles of the I-III-VI2 material in the wurtzite phase to a chalcopyrite phase comprising a semiconductor material, and forming a second conductive material over the semiconductor material, or applying particles comprising a I-III-VI2 material in a wurtzite phase over a conductive material on a substrate, annealing the particles to convert the I-III-VI2 material in the wurtzite phase to a chalcopyrite phase, and forming a buffer material, a semiconductor material, and another conductive material over the particles, or combining a carrier with I-III-VI2 particles comprising chalcopyrite particles and wurtzite particles to form a particle matrix, the chalcopyrite particles having an average diameter less than or substantially equal to an average thickness of the wurtzite particles, applying the particle matrix over a first conductive material overlying a substrate, applying a pressure to the particles to promote adhesion between the particles and the first conductive material, exposing the I-III-VI2 particles to heat to convert the wurtzite particles to additional chalcopyrite particles comprising a first semiconductor material, and forming a buffer material, a second semiconductor material, and another conductive material over the first semiconductor material; and    (4) a semiconductor device comprising a layer of semiconductor material formed by a process comprising depositing a particles comprising a I-III-VI2 material in a wurtzite phase over a substrate, and exposing the particles to heat to convert the I-III-VI2 material in the wurtzite phase to the chalcopyrite phase.