  We propose a novel probe technique capable of performing local
low-temperature spectroscopy on a 2D electron system (2DES) in a semiconductor
heterostructure. Motivated by predicted spatially-structured electron phases,
the probe uses a charged metal tip to induce electrons to tunnel locally,
directly below the tip, from a "probe" 2DES to a "subject" 2DES of interest. We
test this concept with large-area (non-scanning) tunneling measurements, and
predict a high spatial resolution and spectroscopic capability, with minimal
influence on the physics in the subject 2DES.
