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 ch emistry and the electronic structure of CdTe were studied by synchrotr on radiation soft x-ray photoemission spectroscopy and optical emissio n spectroscopy as a function of substrate temperature. The low energy H-2 plasma was generated with a commercial electron cyclotron resonanc e plasma source using pure H-2 with the plasma exposure being performe d at ambient temperature, 100 degrees C, and 200 degrees C. Plasma spe cies were identified with optical emission spectroscopy. In situ photo emission measurements were acquired after each plasma exposure in orde r 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 correla ted in order to relate the plasma species and characteristics to chang es in surface defect chemistry and electronic structure. These measure ments indicate that the H-2 plasma exposure type converts the CdTe(100 ) surface from p- to n-type and passivates defect states.