Ion Incident Angle Dependence of Ridge Shapes Formed on [111] Oriented Gd₃Ga₅O₁₂ by Ion Beam Etching

A ridge pattern is formed on a [111] oriented Gd 3 Ga 5 O 12 (GGG) substrate using an argon ion-beam etching at various ion incident angles between 90° and 45°. The relation between the ridge shapes and the ion incident angles is studied. The applicability of a phosphoric acid treatment after the ion-beam etching to smooth the ridge side wall is also examined. The ridge shape strongly depends on the ion incident angle. The phosphoric acid treatment causes a noticeable change of ridge shape dependent on the GGG crystal structure.