Diffusion barrier cladding in Si/SiGe resonant interband tunneling diodes and their patterned growth on PMOS source/drain regions

Abstract

Si/SiGe resonant interband tunnel diodes (RITDs) employing /spl delta/-doping spikes that demonstrate negative differential resistance (NDR) at room temperature are presented. Efforts have focused on improving the tunnel diode peak-to-valley current ratio (PVCR) figure-of-merit, as well as addressing issues of manufacturability and CMOS integration. Thin SiGe layers sandwiching the B /spl delta/-doping spike used to suppress B out-diffusion are discussed. A room-temperature PVCR of 3.6 was measured with a peak current density of 0.3 kA/cm/sup 2/. Results clearly show that by introducing SiGe layers to clad the B /spl delta/-doping layer, B diffusion is suppressed during post-growth annealing, which raises the thermal budget. A higher RTA temperature appears to be more effective in reducing defects and results in a lower valley current and higher PVCR. RITDs grown by selective area molecular beam epitaxy (MBE) have been realized inside of low-temperature oxide openings, with performance comparable with RITDs grown on bulk substrates.