Electrical characteristics of diodes fabricated in selective Si/Si sub(1-x)Ge sub(x) epitaxial layers

Diodes have been fabricated in layers of Si sub(1-x)Ge sub(x) and silicon deposited selectively on patterned wafers, and the electrical characteristics of the diodes have been examined. For 50 nm thick Si sub(1-x)Ge sub(x) layers containing about 22% Ge, the forward characteristics of larger diodes are nearly ideal. However, the reverse leakage current is higher when the edges of the diode intersect the oxide defining the selectively deposited layers than when the diodes edges are separated from this oxide. The diode characteristics are more ideal when the diode edges are aligned along the (100) directions than when aligned along the (110) directions. Higher-temperature hydrogen pre-treatments before epitaxial deposition can degrade the diode characteristics.