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ABSTRACT The crystallization of amorphous indium oxide thin films with zero to 9.8 wt% SnO, was studied using a combination of in situ MOSS (multibeam optical stress senor) and in situ resistivity measurements. We report that amorphous indium oxide deposited using electron beam evaporation undergoes crystallization in a two part process of amorphous structure relaxation followed by crystallization. MOSS measurements show that the relaxation process corresponds to a densification of the amorphous structure while crystallization results in a molar volume increase. INTRODUCTION Tin-doped indium oxide (ITO) is the transparent conductor of choice for a number of critical technologies including flat panel displays, EMF shielding, and solar cells. Although other transparent conductors are available such as, SnO2:F and Zn(A1)O, ITO is favored because, of the available choices, it offers the highest transmissivity of visible light comb ned with the lowest electrical resistivity. For high performance applications, ITO is deposited on heated substrates (300-400'C) typically using dc-magnetron sputtering of a ceramic target in a controlled oxygen ambient to achieve resistivities of I1.5xl10 4 Qcm. Flat panel display technologies currently under development require deposition of ITO films onto heat-sensitive polymer substrates and polymeric color filters that cannot survive vacuum processing temperatures above 200'C. Under these deposition conditions the optical transmissivity and electrical conductivity of ITO are severely degraded. In fact, physical vapor deposition of ITO at low substrate temperatures may result in the deposition of an amorphous material with lower conductivity and optical transmissivity than the crystalline phase. Remarkably, the amorphous material will undergo solid state crystallization at extremely low temperatures (