Pt/Ti/p-In0.53Ga0.47As low-resistance nonalloyed ohmic contact formed by rapid thermal processing

Abstract

Very low resistance nonalloyed ohmic contacts of Pt/Ti to 1.5×10¹⁹ cm⁻³ Zn‐doped In_0.53Ga_0.47As have been formed by rapid thermal processing. These contacts were ohmic as deposited with a specific contact resistance value of 3.0×10⁻⁴ Ω cm². Cross‐sectional transmission electron microscopy showed a very limited interfacial reacted layer (20 nm thick) between the Ti and the InGaAs as a result of heating at 450 °C for 30 s. The interfacial layer contained mostly InAs and a small portion of other five binary phases. Heating at 500 °C or higher temperatures resulted in an extensive interaction and degradation of the contact. The contact formed at 450 °C, 30 s exhibited tensile stress of 5.6×10⁹ dyne cm⁻² at the Ti/Pt bilayer, but the metal adhesion remained strong. Rapid thermal processing at 450 °C for 30 s decreased the specific contact resistance to a minimum with an extremely low value of 3.4×10⁻⁸ Ω cm² (0.08 Ω mm), which is very close to the theoretical prediction.