Electronic Structure of Semiconducting Films upon Ordering, as Observed by Double-Beam Photoemission

The evolution of the electronic structure of disordered Te and Ge films upon thermal annealing and/or laser irradiation has been traced with use of the newly developed double-beam photoemission technique. In particular, it is shown that, contrary to what occurs in Te films, the onset of short-range crystalline ordering appears abruptly and uniformily within the Ge films, but over a much too short range to avoid →k randomization before emission of the electrons.