Harnessing ferroelectric negative capacitance in Hf _0.5Zr _0.5O ₂-based thin films is promising for applications in nanoscale electronic devices with ultralow power dissipation, due to their ultimate scalability and semiconductor process compatibility. However, so far, it has been unclear if negative capacitance is an intrinsic material property of ferroelectric Hf _0.5Zr _0.5O ₂, or if it is an extrinsic effect caused by specific domain configurations and lateral domain wall motion as seen in perovskite ferroelectrics. Here, symmetric and asymmetric Hf _0.5Zr _0.5O ₂/Al ₂O ₃-based ferroelectric/dielectric heterostructures are investigated to understand the relationship among depolarization, interfacial charge, domain formation, and negative capacitance. To achieve this, detailed electrical characterization is combined with structural data, analytical modeling, and numerical simulations. The findings suggest that negative capacitance in these ferroelectric/dielectric heterostructures is an intrinsic property of the Hf _0.5Zr _0.5O ₂ layer, which has important implications for potential applications. Furthermore, it is experimentally observed that the energy barrier for polarization switching in Hf _0.5Zr _0.5O ₂ is largely independent of the domain configuration and layer thickness, which confirms recent predictions by first principles calculations.