A range of carrier concentrations can be achieved by halogen doping of Y 2 Te 3 depending on the thermodynamic equilibrium at different growth conditions (Table ). For example, while the maximum electron concentration achieved by I doping is 2.0 × 10 20 cm -3 , it is also possible to have much lower electron concentration e.g., 9.2 × 10 16 cm -3 when Y 2 Te 3 is in equilibrium with YTe 3 and YI 3 . This is a direct consequence of two factors: (1) the fundamental dependence of the defect formation energy on the elemental chemical potentials, which are set by the thermodynamic conditions, and (2) charge compensation by acceptor-like defects at certain thermodynamic conditions where they are favorable. As a result, halogen doping of Y 2 Te 3 will require careful consideration of the thermodynamic state to rationally optimize n-type doping.