Abstract
Charging energy (E_C) is essential in quantum dot (QD) devices. Previous studies on PbTe QDs have reported both the presence and absence of E_C. To resolve this ambiguity, we vary the QD size, i.e. the cross-sectional area of PbTe nanowires, and track the evolution of E_C. For large crosssectional areas (∼ 16000 nm²), the PbTe QDs exhibit no measurable E_C, while quantized levels are well resolved. Decreasing this area successively to 5000, 1500, and 500 nm², E_C becomes finite and increases to 80, 160, and 210 μeV, respectively. We further demonstrate the strong tunability of local gates, which can tune the PbTe device from the QD regime to the regime of ballistic transport. These results address concerns regarding the large dielectric constant of PbTe and provide key insights in engineering advanced PbTe quantum devices.