InGaAs Quantum-Well MOSFET Arrays for Nanometer-Scale Ohmic Contact Characterization

We demonstrate InGaAs quantum-well (QW) MOSFET arrays with Mo contact lengths between 40 and 800 nm fabricated by a self-aligned process. A gate pitch of 150 nm is realized, which is the smallest at present for any type of InGaAs FET structure. Fabricated gated MOSFET arrays and gate-less arrays are used to study the properties of nanoscale ohmic contacts in InGaAs MOSFETs with different contact lengths. A three-layer resistive-network model is developed to analyze the contact electrical characteristics. From this paper, we extract a contact resistivity from Mo to n+InGaAs of 8 × 10-9Ω · cm2, and from n+InGaAs to the QW channel of 2 × 10-8Ω · cm2. When benchmarked with other ohmic contact technologies for n-type InGaAs MOSFETs, our refractory metal contact approach represents the lowest film resistivity and is among the lowest contact resistivity that has been demonstrated. The contact model developed here infers a contact resistance from the Mo contact to the channel of 260 Ω · μm for a contact length of Lc= 10 nm. This suggests that further research on low-resistance ohmic contacts is required before InGaAs MOSFETs can deliver the required performance.