AuBe/p-InGaAsP contact formed by rapid thermal processing

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Abstract
Alloyed ohmic contacts of AuBe (1% Be by weight) to 5×1018 cm−3 Zn‐doped p‐InGaAsP (λg=1.3 μm) were fabricated by rapid thermal processing and its performance was compared to those of the contacts formed by conventional furnace heating. The specific contact resistance decreased from a value of 4.9×10−4 Ω cm2 as‐deposited to a value of 4.9×10−7 Ω cm2 as a result of rapid thermal processing at 420 °C for 30 s. This value was much lower than the value of 3.9×10−6 Ω cm2 obtained as a result of furnace heat treatment at 420 °C for 10 min. Rapid thermal processing at higher temperatures caused a sharp increase of the specific contact resistance. Auger depth profiling indicated that the degradation of the contact electrical performance at temperatures of 450 °C or higher were caused by intensive localized interactions between the AuBe and the InGaAsP and out‐diffusion of all the quaternary elements toward the surface of the contact. The effective stress in the alloyed layer, normalized to the initial AuBe thickness of 80 nm, was tensile with a value of 7×109 dyn cm−2, and was less sensitive to the alloying parameters (time and temperature) than was the contact resistance.