  Graphene nanoribbons (GNRs) have attracted a strong interest from researchers
worldwide, as they constitute an emerging class of quantum-designed materials.
The major challenges towards their exploitation in electronic applications
include reliable contacting, complicated by their small size ($<$50 nm), as
well as the preservation of their physical properties upon device integration.
In this combined experimental and theoretical study, we report on the quantum
dot (QD) behavior of atomically precise GNRs integrated in a device geometry.
The devices consist of a film of aligned 5-atoms wide GNRs (5-AGNRs)
transferred onto graphene electrodes with a sub 5-nm nanogap. We demonstrate
that the narrow-bandgap 5-AGNRs exhibit metal-like behavior resulting in linear
IV curves for low bias voltages at room temperature and single-electron
transistor behavior for temperatures below 150~K. By performing spectroscopy of
the molecular levels at 13~K, we obtain addition energies in the range of
200-300 meV. DFT calculations predict comparable addition energies and reveal
the presence of two electronic states within the bandgap of infinite ribbons
when the finite length of the 5-AGNRs is accounted for. By demonstrating the
preservation of the 5-AGNRs electronic properties upon device integration, as
demonstrated by transport spectroscopy, our study provides a critical step
forward in the realisation of more exotic GNR-based nano-electronic devices.
