Study of the structure and properties of the Ti/GaAs interface

Reactions between Ti thin films and (100) n-type GaAs substrates in the temperature range 250–600 °C were studied by Auger sputter profiling and correlated with electrical measurements. Annealing above 400 °C, caused significant intermixing of the Ti and GaAs, resulting in a layered structure of the type Ti/Ti:Ga/Ti:As/GaAs similar to the results of Wada et al. [Appl. Phys. Lett. 29 (1976)]. Both Ti–As and Ti–Ga compounds were identified by electron diffraction (Kim and Sinclair, unpublished). The effects of annealing on the Schottky barrier behavior were studied by a combination of I–V, C–V, and photoresponse measurements. Upon reaction of the Ti with the substrate, the barrier height saturated at a value of roughly 0.80 eV, a 100-meV increase over the as-deposited value. The effect interfacial impurities left by chemical cleaning procedures on the properties of the Ti/GaAs system was also investigated. Surface preparations, characterized by x-ray photoelectron spectroscopy and Auger electron spectroscopy were found to have a small (barrier heights ranged from 0.69 to 0.73 eV) effect on the as-deposited barrier height.