Knowledge Bank

Thermal oxidation and electrochemical anodization of III-V semiconductor surfaces produce protective oxide coatings and an interfacial region where localized thermally induced chemical reactions can occur. The system GaAs - oxide ($Ga2O3+As2O3$) was studied using a Raman backscattering method. The interfacial reaction $2GaAs+As2O3\to Ga2O3+4As$ occurs slowly at $350\circ C$ and rapidly at $500\circ C$ producing amorphous and crystalline arsenic that is localized in a region near the semiconductor surface. Chemical etching experiments reveal that amorphous arsenic is closer to the GaAs surface than the crystalline form and using thin oxide films ($d\le 300$ {\AA}), the minimum detection limit for arsenic is the order of 10 {\AA}.