Current Saturation in Field Emission from H-Passivated Si Nanowires

Abstract

This paper explores the field emission (FE) properties of highly crystalline Si nanowires (NWs) with controlled surface passivation. The NWs were batch-grown by the vapor-liquid-solid process using Au catalysts with no intentional doping. The FE current-voltage characteristics showed quasi-ideal current saturation that resembles those predicted by the basic theory for emission from semiconductors, even at room temperature. In the saturation region, the currents were extremely sensitive to temperature and also increased linearly with voltage drop along the nanowire. The latter permits the estimation of the doping concentration and the carrier lifetime, which is limited by surface recombination. The conductivity could be tuned over 2 orders of magnitude by in situ hydrogen passivation/desorption cycles. This work highlights the role of dangling bonds in surface leakage currents and demonstrates the use of hydrogen passivation for optimizing the FE characteristics of Si NWs.

A Comparative Study of Field Emission From Pristine, Ion‐Treated and Tungsten Nanoparticle‐Decorated p‐Type Silicon Tips

“…The FE current only increased by 25% under light illumination, that is, decorated tips showed four times lower light sensitivity than pristine silicon tips. This indicates that the field penetration effect is weakened by a tungsten nanoparticle due to the electrostatic screening of the silicon tip apex and the increase of the density of surface states . As expected, FIB‐treated tips decorated with metallic tungsten nanoparticles had linear FN plots without saturation and showed no light sensitivity (Figure d).…”

“… for details) the FE current in the saturation region increased approximately by a factor of 2. Such kind of saturation as well as the sensitivity to light and temperature are usually observed for field emitters made of p‐type semiconductors . At low voltages, the FE current is determined by FN‐tunneling processes from the conduction band of the semiconductor into the vacuum.…”

“…Practical applications usually require improvement and tailoring of FE characteristics of as‐produced silicon tips by modification of their surfaces using different methods. For instance, significant modification of the current saturation occurs after decoration of a bare silicon tip by a nanoparticle located on the tip apex . An additional enhancement of the electric field and a corresponding reduction of the FE threshold field can be achieved due to nanoparticle deposition on the tip .…”

A Comparative Study of Field Emission From Semiconducting and Metallic Single‐Walled Carbon Nanotube Planar Emitters

“…First, semiconducting nanotubes have higher electrical resistance and during emission larger voltage drops can occur inside them which can cause pronounced saturation-like deviation from the classical FN behavior. [21] Moreover, the saturation behavior which is usually observed for semiconducting tip emitters [22,23] can be also explained by the formation of a highly resistive region (depletion zone) at the emitter apexes due to the penetration of the electric field. [24] The depletion zone limits the tunnelling current and results in nonlinear FN plots.…”

Field emission measure of the time response of individual semiconducting nanowires to laser excitation

“…8 The drops were determined by the total energy distributions (TEDs) of the emitted electrons which, when combined with the measured total current, becomes a type of two point transport measurement. 13 In the saturation region, measured voltage drops along the NWs reached up to several hundreds of volts 11,12 and were T-dependent. These measurements allowed us to identify the carrier transport mechanisms 14 in our SiC NWs, which is difficult using only FN plots as measured by most authors (e.g.…”