Study On Growth And Optical Emission Of A-SiN_x: H Films Prepared By ECR-CVD

Electron cyclotron resonance plasma enhanced chemical vapor deposition is used to produce amorphous hydrogenated silicon nitride (a-SiN_x:H) under different gas flow ratio of SiH₄ (80% Ar diluted) and NH₃(N₂). Optical emission spectroscopy is used to investigate the plasma behavior, while Fourier Transform Infrared (FTIR) is used to measure the bond configuration of a-SiN_x:H films. It is found that the variation of Si radical concentration in the plasma caused decrease of the film growth rate with the increase of NH₃ (N₂)flow rate. The blue shift for Si-N and Si-H stretching mode with the increasing NH₃ flow rate can be attributed to more N atoms with a higher electro-negativity bonded into the a-SiN_x:H film. The amount of bonded hydrogen into the a-SiN_x:H films is calculated to be a rather low level, about 15% or so. The growth mechanism of a-SiN_x:H films is also discussed.We studied the photoluminescence and electro-luminescence of the films. When the films are Si-riched, the luminescence peak position are blue-shifted with the decrease of the excess Si content. When the films are N riched, the luminescence peak position stop shifting. The result demonstrate that the blue-shift of luminescence peak position with decreasing excess Si content was attributed to the quantum confinement effect in a-Si QDS, the luminescence associate to the inherently imperfect Si and N dangling bonds when the films are N-riched.