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

Abstract

SiO_xN_y capped infrared rapid thermal annealing was investigated for activating high dose (>7×10¹³ cm⁻²) Si implants in GaAs. The SiO_xN_y 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 SiO_xN_y 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.