Effects of adding elements M (M = C, B, Mn, Al and Al + Co) on stability of amorphous semiconducting Fe–Si films

Abstract

Amorphous semiconducting Fe–Si film with direct optical band gap (Eg) has become a promising candidate material for optoelectronic devices. It can avoid the difficulties of crystalline materials preparation. The key to expanding its applications is to further improve its stability under the premise of maintaining the semiconducting performance. In the present paper, the amorphous Fe–Si–M (M = C, B, Mn, Al, Al + Co) films were prepared on the single-crystal Si(100) and Al2O3(0001) substrates by radio frequency (RF) magnetron sputtering to discuss the effects of the third (fourth) elements M on the films’ performance. The result shows that all the added elements except for Al have no obvious effects on the Eg of the amorphous Fe–Si films. The amorphous Fe–Si–M and Fe–Si films have the same variation trends on the electrical resistivity (ρ). However, the conductivity of the films slightly increase after adding the third (fourth) elements. Both the theoretical calculation and experimental results show that the third element C, B and Al can significantly improve the amorphous stability, and the initial crystallization temperatures (Tx) of the films increase with the third element content. Particularly, the Tx of amorphous Fe–Si–C films are over 500 °C, the highest Tx is up to 581 °C, which is ~ 100 °C above that of the a-Fe–Si film with the same Fe content. Therefore, to select the added element M and its content properly can greatly improve the stability of the film without significant effect on the Eg and ρ of the amorphous Fe–Si–M films.