Advancing Laser-ARPES: The Development of a Bias Voltage-Enhanced System

Conventional Laser-ARPES systems excel in providing high energy resolution, large scattering cross-sections, and increased bulk sensitivity. However, the typical photon energy, usually below 11 eV, combined with the limited detection range of the hemispherical analyzer, restricts the momentum space captured in a single measurement to a small portion of the full Brillouin zone. Here, we have developed a bias voltage-enhanced Laser-ARPES system that significantly expands the accessible momentum space in a single measurement. By placing an insulating sapphire piece between the sample and ground, we introduce a bias voltage that creates a uniform electric field between the sample and the analyzer. This field accelerates and deflects emitted electrons at large angles, directing them toward the analyzer entrance for collection. Our system not only preserves the core strengths of Laser-ARPES but also substantially improves detection efficiency for low photon energy ARPES systems, pushing the boundaries of its capabilities.