Efficient Visible Luminescence from Hydrogenated Amorphous Silicon
Original Publication Date: 1982-Aug-01
Included in the Prior Art Database: 2005-Feb-10
We report efficient broadband visible photoluminescence in a-Si:H films, i.e., amorphous SiH(x) (0.2 < x < 0.5) prepared by homogeneous chemical vapor deposition (HOMOCVD). For growth temperatures, T(s), from 200-500 degrees C, an optical gap approx. 1.6 eV obtains, and typical 1.4 eV a-Si:H luminescence is observed at 5 degrees K. For growth below 200 degrees C, the gap increases sharply with decreasing T(s) and new 0.35 eV-wide emission develops, shifting to higher energies with the gap. In room temperature deposited films, the gap reaches 2.6 eV and emission peaks near 1.99 eV. Occurrence of this new band correlates with large hydrogen incorporation (20-50 at.%.), low EPR spin density (< 4x10/16/ cm/-3/ ), large optical gap (1.6-2.6 eV) and polysilane chain formation.