MICROSTRUCTURAL STUDY OF TI PT/AU CONTACTS TO P-INGAAS/

Reactions that occur al the Ti/InGaAs interface during annealing (less than or equal to 350 degrees C) of Ti/Pt/Au ohmic contacts to p-type InGaAs have been studied using transmission electron microscopy (TEM). Two different InGaAs surfaces were studied; one given a hydrophobic e tch (1% HF) prior to metallization deposition and one oxidized (approx imate to 3 nm thick) in a UV ozone environment prior to metallization. Qualitatively, the reactions were the same for both types of InGaAs s amples, i.e. InGaAs decomposition began at low annealing temperatures resulting in the formation of TiAs, metallic In and Ga-rich InGaAs. Lo w temperature reactions were enhanced for the UV ozone treated InGaAs surfaces, due to Ti reduction of the oxide layer. Higher temperature a nnealing did not change the reaction products, only the extent of reac tion. The In that formed had a pyramidal shape and exhibited preferred growth within the InGaAs-the base sides were parallel to InGaAs (110) planes, while the particles protruded into the InGaAs along InGaAs (1 11) planes. (C) 1997 Elsevier Science S.A.