Study of Ohmic Contact on p-InGaN Using MIGS Model

Abstract

The formation of ohmic contact to p-InGaN has been analyzed here using the Metal induced Gap States (MIGS) model with an ultrathin interfacial layer of insulator. The position of Fermi level and barrier height modulation has been investigated for two different combinations of Metal-Insulator with p-InGaN. In case of p-InGaN with 2nm layer of NiO, Au formed a barrier height of 0.49 eV. The contact resistivity for $\mathbf{Au}/\mathbf{NiO}(\pmb{2}\ \mathbf{nm})/\mathbf{p-}\mathbf{In}_{\pmb{0.48}}\mathbf{Ga}_{\pmb{0.52}}\mathbf{N}$ is found to be $\pmb{2.35\times 10^{-4} \Omega-}\mathbf{cm}^{\pmb{2}}$ at 300K and $\pmb{1.15\times 10^{-4} \Omega-}\mathbf{cm}^{\pmb{2}}$ at 600K. It is also observed that the metal with higher work function gives lower barrier height and contact resistivity in case of p-InGaN. For Pt/AI2O3(2 nm)/p-In0.48Ga0.52N, the barrier height becomes 0.312 eV and the contact resistivity is estimated as $\pmb{1.9\times 10^{-4}\Omega-} \mathbf{cm}^{\pmb{2}}$ at 300K and $\pmb{0.75\times 10^{-4}\Omega-}\mathbf{cm}^{\pmb{2}}$ at 600K. Thus, Pt contact shows better performance than Au contact to p-InGaN. This information of MIS contact could be a good insight for conventional CMOS in case of source/drain applications.