Punchthrough-Diode-Based Bipolar RRAM Selector by Si Epitaxy

We propose an epitaxial punchthrough diode for bipolar resistance RAM (RRAM) selector application. Epitaxial Si:C process is used to deposit $\hbox{n}^+/\hbox{p}/\hbox{n}^+$ layers which are fabricated into 300-nm-diameter vertical punchthrough diodes. High on-current density of $> \hbox{1}\ \hbox{MA/cm}^{2}$ and high on/off current ratio of $>$ 250 and $>$ 4700 (at opposite polarities) are observed. A switching speed of $<$ 10 ns is measured. On-voltage designability is demonstrated by tuning the p-region doping and length. The comparison of experimental $IV$ with Sentaurus TCAD-simulated $IV$ characteristics confirms the punchthrough mechanism. Comparison with other bipolar RRAM selector technologies highlights the overall advantages of punchthrough-based selector.