Planar nanoscale vacuum channel transistors based on resistive switching.

Resistance switching (RS) offers promising applications in a variety of areas. In particular, silicon oxide (SiOx) under RS can serve as electron sources in new types of miniature vacuum electron tubes. In this work, planar nanoscale vacuum channel transistors (NVCTs) with graphene electrodes and RS SiOxelectron sources were developed. In each RS-NVCT, the resistance between the ground and the gate underwent high-low-high transitions, which resulted from formation and subsequent rupture of Si conducting filaments. Electrons were emitted from the post-reset Si filaments and the current received by the collector (IC) was well controlled by the gate voltage (VG). The transfer characteristics reveal thatICwas quite sensitive toVGwhen RS occurred. WithVGsweeping from 0 to -20 V, the obtained subthreshold swing (SS) of 76 mV dec-1was quite close to the theoretical limit of the SS of a field effect transistor at room temperature (60 mV dec-1). The largest ON/OFF ratio was of the order of 106. The output characteristics of the devices indicate that the dependence ofICon the collector voltage (VC) weakened at highVCvalues. These results demonstrate the application potential of RS-NVCTs as either switching devices or amplifiers.

Metal-Air Field Emission Devices - Nano Electrode Geometries Comparison of Performance and Stability.

Air-channel devices have a special advantage due to the promise of vacuum-like ballistic transport in air, radiation insensitivity, and nanoscale size. Here, achieving high current at low voltage along with considerable mechanical stability is a primary issue. The comparative analysis of four planar and metallic electrode-pair geometries at 10 nm channel length is presented. The impact of nano-electrode-pair geometries on overall device performance is investigated. Air-channel devices are operated at the ultra-low voltage of 5 mV to demonstrate the device dynamics of air-channel devices at low power. Investigations focus on the direct tunneling (DT) mechanism which is dominant in the low-voltage regime. Comparative analysis of different electrode-pair geometries reveals two orders of magnitude increment in the current just by modulating the electrode-pair structure. Theoretical analysis suggests that the emission current is directly related to the active junction area within the metal-air-metal interface at the direct tunneling regime. The geometry-dependent mechanical stability of different electrode pairs is compared by imaging biasing triggered nanoscale structural changes and pulsed biasing stress analysis. The results and claims are confirmed and consolidated with the statistical analysis. Experimental investigations provide strong directions for high-performance and stable devices. In-depth theoretical discussions will enable the accurate modeling of emerging low-power, high-speed, radiation-hardened nanoscale vacuum electronics.