Self Aligned van der Waals Heterojunction Diodes and Transistors.
A general self aligned fabrication scheme is reported here for a diverse class of electronic devices based on van der Waals materials and heterojunctions. In particular, self alignment enables the fabrication of source gated transistors in monolayer MoS2 with near ideal current saturation characteristics and channel lengths down to 135 nm. Furthermore, self alignment of van der Waals p n heterojunction diodes achieves complete electrostatic control of both the p type and n type constituent semiconductors in a dual gated geometry, resulting in gate tunable mean and variance of antiambipolar Gaussian characteristics. Through finite element device simulations, the operating principles of source gated transistors and dual gated antiambipolar devices are elucidated, thus providing design rules for additional devices that employ self aligned geometries. For example, the versatility of this scheme is demonstrated via contact doped MoS2 homojunction diodes and mixed dimensional heterojunctions based on organic semiconductors. The scalability of this approach is also shown by fabricating self aligned short channel transistors with subdiffraction channel lengths in the range of 150 800 nm using photolithography on large area MoS2 films grown by chemical vapor deposition. Overall, this self aligned fabrication method represents an important step toward the scalable integration of van der Waals heterojunction devices into more sophisticated circuits and systems.
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