Origin of the crystalline orientation dependence of the electrical properties in tin-doped indium oxide films

Crystalline-orientation-dependent carrier density in sputter-deposited tin- doped indium oxide (ITO) films was discovered by the epitaxial growth techn ique. Despite identical Sn concentration, (111)-epitaxial films always show ed a lower carrier density compared to films of other crystalline orientati ons. A crystallographic investigation of the ITO material revealed that the crystalline growth along < 111 > accommodates the larger amount of interst itial oxygen atoms (O-int). These atoms reduce the density of free electron s when combined with substitutional tin atoms which act as donors in ITO ma terial. Thus the peculiarity of the electrical properties of(111)-epitaxial films is attributed to the crystalline orientation dependence of the popul ation of O-int. (C) 2001 Elsevier Science B.V. All rights reserved.