A z-axis Tunneling Microscope for Advanced Undergraduate Labs

The scanning tunneling microscope (STM) is a powerful tool for studying electronic structure in an advanced lab setting. We have developed a simplified alternative to the STM that restricts tip motion to one dimension: the z-axis tunneling microscope (ZTM). Here, the z-axis lies along the tip-sample separation. Students are able to observe the exponential dependence on tunneling current with tip-sample gap, and observe qualitative differences in the electronic density of states between metals, semimetals, and semiconductors. Data collected by advanced lab students as part of their coursework will be presented. The ZTM is simpler and less costly to build than an STM, expanding access to a subset of STM experiments to more learners.