On the electrical and charge conduction properties of thermally evaporated MoO_x on n- and p-type crystalline silicon

Abstract

In this work, the electrical and charge conduction characteristics of a contact structure featuring thermally evaporated MoO_x, deposited on n- and p-type crystalline silicon (c-Si), are extensively investigated by room temperature current–voltage (I–V), transmission line measurements (TLM), and temperature-dependent current–voltage measurements (I–V–T). XRD diffraction spectrum shows that the deposited MoO_x film exhibits amorphous nature. From TLM measurements, the values of contact resistivity are calculated to be ${\rho_{\rm {c}}}$: 55.9 mΩ-cm² for Ag/MoO_x/n-Si and ${\rho_{\rm {c}}}$: 48.7 mΩ-cm² for Ag/MoO_x/p-Si. The barrier parameters such as barrier height (${{\phi }_{\mathrm{e}}}$) and ideality factor (${n}$) are investigated by the thermionic emission theory for I–V and I–V–T measurements. The ${{\phi }_{\mathrm{e}}}$, ${n}$, and conventional Richardson plot demonstrate resolute temperature dependency, obeying the barrier height of Gaussian distribution model. The uniform barrier height values are calculated to be ${{\phi }_{\mathrm{b}}}$:1.24 eV for Ag/MoO_x/n-Si and ${{\phi }_{\mathrm{b}}}$:0.66 eV for Ag/MoO_x/p-Si from the extrapolation of ${{\phi }_{\mathrm{e}}}$ at ${n}$ ${=}$ 1 of the linear fitting of the variation with the experimental barrier height ${{\phi }_{\mathrm{e}}}$ with ideality factor. The activation energy (${{E}_{\mathrm{a}}}$) and Richardson constant (A*), obtained from Richardson plot, are much smaller than ${{\phi }_{\mathrm{b}}}$ and the theoretical values of n- and p-type c-Si. The modified Richardson plot yields more reliable Richardson constant and homogeneous barrier height values of 106.2 Acm⁻² K⁻² and 1.21 eV, 23.4 Acm⁻² K⁻² and 0.63 eV for Ag/MoO_x/n-Si and Ag/MoO_x/p-Si heterostructures, respectively. The results demonstrate that thermally evaporated MoO_x has particular advantages due to its good rectifying characteristics such as the extra enhancement to barrier height and low contact resistivity for interfacial layer applications.