Coating liquid for forming n-type oxide semiconductor film, method for producing n-type oxide semiconductor film, and method for producing field-effect transistor

A coating liquid for forming a semiconductor oxide film comprising:

• a Group A element, which is a preventer from generation of oxygen vacancies, and which is at least one selected from the group consisting of Zr, Hf, Ce, Si, and Ge;
• a Group B element, which is a main constituting element of a bottom of a conduction band of the semiconductor oxide film, and which is at least one selected from the group consisting of Ti and Sn;
• a Group C element, which is a dopant, and which is at least one selected from the group consisting of Group 5 elements, Group 6 elements, Group 7 elements, Group 8 elements, Group 9 elements, Group 10 elements, Group 15 elements, and Group 16 elements;
• and
• a solvent,
• wherein a valence of the Group A element is the same as that of the Group B element;
• wherein the Group C element is at least one selected from the group consisting of V, Nb, Ta, Cr, Mo, W, Re, Ru, Os, Ir, Pt, Sb, Bi, Se, and Te,
• wherein the coating liquid does not include a Group 1 element, a Group 2 element, a Group 3 element, a Group 11 element, a Group 12 element, and a Group 13 element, except that Ce of the Group 3 elements may be present, and
• wherein a total number of atoms of the Group A element (NA) and a total number of atoms of the Group B element (NB) satisfy the following formula:
• 0.02≤[NA/NB]≤0.2.