Structural and optical properties of (In,Ga)_2O_3 thin films and characteristics of Schottky contacts thereon

摘要

We report on structural and optical properties of a (In_xGa_(1-x))_2O_3 thin film having a monotonic lateral variation of the indium content x (0 ≤ x ≤ 0.9). The growth condition for each In content is similar allowing precise determination of the dependence of material properties on x. For low In content (x ＜ 0.15) the thin film has monoclinic crystal structure; for highest In contents (x ＞ 0.8) the cubic bixbyite phase is predominant. For intermediate alloying we observe additionally the rhombohedral InGaO_3(Ⅱ) crystallographic phase. The optical band-gap decreases systematically with increasing indium content and has a linear dependency on x for parts of the sample having the monoclinic phase, only. Further, properties of Pt Schottky diodes are reported for monoclinic (In_xGa_(1-x))_2O_3 and photo response measurements for x ＜ 0.1.