Integration of silicon-based tunnel diodes with CMOS: An RIT-OSU-NRL-NSF effort

Resonant tunneling diodes (RTDs) are promising band gap engineered heterostructures that exhibit a distinctive negative differential resistance (NDR) that can be exploited for various electronic functions. Large scale integration of RTDs with heterojunction field effect transistors (HFETs) have been demonstrated in III-V compound semiconductors. Since the current microelectronics industry has evolved around silicon CMOS technology, it is of great interest if RTDs can be integrated with Si CMOS circuitry. Silicon-based tunnel diodes have great potential for this integration. Ohio State University and RIT have received funding from the National Science Foundation to address these issues with the Naval Research Laboratory. Among the integration strategies investigated, placing of tunnel diodes on the source/drain regions of MOS transistors has been found to be most promising. A test chip has been designed to study the process integration. Preliminary studies have shown that the tunnel diode fabrication steps have negligible influence on the threshold voltage and transconductance of the MOS transistors.