Metal-induced low temperature activation and La2O3 passivation of germanium N+/P and P+/N Junctions

We employ Pt metal-induced dopant activation (MIDA) process to activate the P and B dopants in Ge at low temperatures in the range between 350 and 380degC and fabricate high performance Ge N⁺/P and P⁺/N diodes. In N⁺/P we have obtained record forward current density J_forw ~ 370 A/cm² at -2V bias with a very good I_forw/I_rev ratio in excess of 2times10⁴. The Ge P⁺/N diodes also have very high J_forw in excess of 200 A/cm² at +1 V but they suffer from high reverse current which is dominated by increased periphery leakage due to unpassivated interface states in depletion. We show that by using appropriate La₂O₃ passivation-isolation layer, the periphery leakage is minimized and the reverse current is improved by an order of magnitude. The fabrication of high forward current diodes at low temperature takes full advantage of the high carrier mobility in Ge allowing also 3D (vertical) co-integration of Ge and Si transistors.