Sputtered Ni-P as an ohmic contact to n-InP, p-InGaAs and as a diffusion barrier

Ni2P is a metallic conductor with a bulk resistivity of 32 µΩ . cm. Films of Ni2P can be sputter-deposited in both the amorphous and crystalline forms by varying the sputtering parameters. The amorphous to crystalline transition has been found to take place at about 250 °C and sufficient grain growth to exhibit X-ray reflections takes place by 400 °C. In both forms, films of Ni2P have been found to form ohmic contacts to n-InP (Sn doped 2 × 10¹⁸cm^-3) p-InGaAs (Zn-doped 8 × 10¹⁸cm^-3) with sufficiently low sheet resistivity and specific contact resistance to be useful as a metallization layer in most devices. It was also found that up to 400 °C, amorphous (as sputtered) films of Ni2P function as efficient diffusion barriers between an outer Au layer and the III-V substrate. It is possible, therefore, for amorphous (as sputtered) films of Ni2P to function simultaneously both as a metallization layer and diffusion barrier.