Physical properties of room temperature deposited B-C-N-O films prepared by dual-ion-beam deposition

B-C-N-O films with various compositions were prepared at room temperature using dual-ion-beam deposition. The films are divided into three groups, with C contents below 10 at.%, between 10 and 35 at.%, and above 35 at.%, respectively. The films of the first group are dominated by the existence of a B-O phase. They have wider optical band gaps E-g, and are therefore more transparent and insulating. The volume fraction of the B-O phase decreases with increasing C content, thereby leading to a drop in the hardness H. The second group of films contains a h-BN phase, and so have smaller E-g and higher room temperature electrical conductivity sigma(room). H rises and approaches that of h-BN when the C content reaches 35 at.%. The third group of films contains a large fraction of a graphite phase, which greatly affects the films properties, leading to a further reduction of E-g and a rise in sigma(room). H becomes lower with increasing C content. This work demonstrates that the optical, electrical and mechanical properties of B-C-N-O films can be tailored by adjusting the composition. (C) 1999 Elsevier Science S.A. All rights reserved.