A method for manufacturing a GaN-based semiconductor device in which an ohmic contact can be provided between the semiconductor layer and the electrode material. The silicate materials contain silanol groups which are reactive to form derivative compositions useful for water purification to remove heavy meal cations. Validation is performed by enforcing a series of validation rules on an appropriate subject. The LED chips are arranged on the base substrate so as to face one another at a vertex forming the larger interior angle in plan view. The inclusion of a stopping criterion improves the computational speed of FRACTA.