  We present the first direct study of charge density wave (CDW) formation in
quasi-2D single layer LaTe_2 using high-resolution angle resolved photoemission
spectroscopy (ARPES) and low energy electron diffraction (LEED). CDW formation
is driven by Fermi surface (FS) nesting, however characterized by a
surprisingly smaller gap (50meV) than seen in the double layer RTe_3 compounds,
extending over the entire FS. This establishes LaTe_2 as the first reported
semiconducting 2D CDW system where the CDW phase is FS nesting driven. In
addition, the layer dependence of this phase in the tellurides and the possible
transition from a stripe to a checkerboard phase is discussed.
