Nonalloyed ohmic contacts to Si-implanted GaAs activated using SiOxNy capped infrared rapid thermal annealing

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Abstract
SiOxNy capped infrared rapid thermal annealing was investigated for activating high dose (>7×1013 cm−2) Si implants in GaAs. The SiOxNy encapsulation resulted in enhancement in electrical activation. An electron concentration as high as 9×1018 cm−3 was obtained by 1120 °C, 5‐sec annealing using an SiOxNy encapsulant with 1.75 refractive index. Nonalloyed ohmic contacts were formed by depositing AuGe‐Ni on a heavily doped n‐type layer activated by this technique, where a 9×10−5 Ω cm2 specific contact resistance was obtained. Furthermore, low‐temperature (300 °C) alloying significantly improved a specific contact resistance to as low as 6×10−6 Ω cm2 while keeping a smooth morphology. These techniques, including low‐temperature alloying, are promising for GaAs and its heterostructure device applications.