CHEMISTRY AND ELECTRONIC-STRUCTURE OF THE H-2 PLASMA PASSIVATED SURFACE OF CDTE

The effects of low energy H-2 plasma exposure on the surface defect chemistry and the electronic structure of CdTe were studied by synchrotron radiation soft x-ray photoemission spectroscopy and optical emission spectroscopy as a function of substrate temperature. The low energy H-2 plasma was generated with a commercial electron cyclotron resonance plasma source using pure H-2 with the plasma exposure being performed at ambient temperature, 100 degrees C, and 200 degrees C. Plasma species were identified with optical emission spectroscopy. In situ photoemission measurements were acquired after each plasma exposure in order to observe changes in the valence band electronic structure as well as changes in the Cd 4d and Te 4d core lines. The results were correlated in order to relate the plasma species and characteristics to changes in surface defect chemistry and electronic structure. These measurements indicate that the H-2 plasma exposure type converts the CdTe(100) surface from p- to n-type and passivates defect states.