Evidence for the Neutralization of Boron in Silicon Using Surface Analysis Techniques

Interactions between the shallow acceptor boron and hydrogen in single crystal, polycrystalline, and amorphous Si are investigated. Low-temperature secondary ion mass spectrometry depth-compositional profiles indicate a definite interaction between the boron concentration and the hydrogen penetration in single crystals and at grain boundaries. The bonding of the H is identified to be directly to the Si rather than to the B, and is confirmed by infrared measurements. Electrical neutralization of the B by hydroxyl-group bonding is also reported at oxygen-rich Si grain boundaries. No similar relationships between P concentration and H penetration are observed. In amorphous Si material, the B-doping level has only a limited effect on the hydrogen penetration which seems to be controlled instead by structural diffusion mechanisms.