Depth dependence of hydrogenation using electron cyclotron plasma in GaAs-on-Si solar cell structures

We have studied the effect of hydrogen-plasma exposure on GaAs-on-Si solar cell structures using electron cyclotron resonance (ECR). An increase in ph otoluminescence (PL) intensity near the GaAs/Si interface is found after th e H-plasma exposure and 400 degrees C annealing, indicating passivation of threading dislocations by diffused hydrogen atoms. Secondary ion mass spect roscopy depth profiles of hydrogen concentration [H] for the ECR-plasma exp osed solar cell structures have shown that the [H] near the GaAs/Si interfa ce increases after the 400 degrees C annealing, which is in good agreement with the PL result. On the other hand, it is found that the [H] near the su rface simply decreases with prolonged annealing time while the [H] near the GaAs/Si interface remains unchanged, which is favorable to the improvement of the conversion efficiency. (C) 1999 American Vacuum Society. [S0734-210 1(99)00802-7].