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There are more or less dopants or defects existing in nanomaterials, so they usually have different conduct-types even for the same substrate. Therefore, fast identification of the conduction-type of nanomaterials is very essential for their practical application in functional nanodevices. Here we use the field emission (FE) technique to research nanomaterials and establish a generalized Schottky-Nordheim (SN) model, in which an important parameter λ (the image potential factor) is first introduced to describe the effective image potential. By regarding λ as the criterion, their energy-band structure can be identified: (a) λ = 1: metal; (b) 0.5

Lanthanum hexaboride (LaB6) nanostructures have attracted much attention in recent years because they exhibit high electrical conductivity and thermal conductivity, low work function and high chemical stability, and can be expected to be an ideal cold cathode electron source for power device applications. Although some groups have developed means to grow LaB6 nanostructures and investigated their emission properties, the moderate synthesis of the LaB6 nanostructure cathode with high-performance is still a challenging issue. Here we developed a simple one-step chemical vapour deposition (CVD) method to prepare the LaB6 nanowire cold cathode film. The LaB6 nanowires have a mean length of tens of micrometres and their average diameter is about 100 nm. The formation of the nanowires is attributed to the synergy of the vapour–liquid–solid (VLS) and vapour–solid (VS) mechanisms. The LaB6 nanowires are found to have a low turn-on (2.2 V μm−1) and threshold field (2.9 V μm−1) as well as nice field emission (FE) stability with a current fluctuation of only 1.7%. And their emission current can reach 5.6 mA (16.7 mA cm−2) at 4.1 V μm−1, which is large enough for the high-current requirements of cathodes used in power devices. Moreover, the LaB6 nanowires still retain excellent performance even if the operation temperature is raised up to 773 K. It is noted that the LaB6 nanowire film exhibits quite different emission behaviours during a temperature cycling between room temperature and 773 K. The adsorption and desorption of oxygen onto and from the nanowire's surface is suggested to explain the discrepancy of such emission properties based on a series of our designed experiments. Most importantly, the LaB6 nanowire cathode film can almost recover to the original excellent FE performances after detachment of the surface oxygen molecules, which suggests that they should be ideal cathode nanomaterials for power device applications.

SmB 6 is believed as an ideal candidate for FE applications because of their unique properties. Up to date, the effect of image potential on the field emission (FE) behaviors of one-dimensional nanostructures is still unclear in experiments, and thus it becomes a challenging issue for the researchers. In this paper, the effect of image potential on FE properties of SmB 6 nanowires are detailed studied by combination of experimental results and the generalized Schottky-Nordheim (SN) model. The experimental results show that they have a turn-on field of 3.4 V/μm (at 10 μΑ/cm2). Meanwhile, the image potential factor of SmB 6 nanowires is calculated to be equal to 1 based on our model, which is resemble to ideal metal plane.

Lanthanum hexaboride (LaB 6 ) nanowires have attracted much attention due to their outstanding physical properties. In order to enhance the developments of LaB 6 nanowires, it is essential to study the field emission (FE) properties of LaB 6 nanowires in different environments. Here, we investigate the effect of oxygen (O 2 ) on the FE behaviors of LaB 6 nanowires. And it is found that the oxygen content attaching on the surface of LaB 6 nanowires strongly affect their FE properties.

As a typcial kondo insulator, SmB 6 has attracted most of attention in recent years. But their corresponding nanostructures are hard to fabricate due to the growth technique. In this paper, uniform SmB 6 nanocone arrays have been successfully fabricated by a simple chemical vapor deposition (CVD) method. The field emission (FE) behaviors of SmB 6 nanocone arrays were investigated to reveal their surface properties. FE measurement results show that SmB 6 nanocone arrays have a low turn-on electric field of 1.84 V/μm (at 10 μA/cm2) and good emission stability, which may have potential applications in FE area.

The B/LaB 6 hierarchical heterojunction nanostructures have been successfully fabricated on Si substrate by CVD technique. The branch-like morphology may be beneficial to improving their field emission (FE) properties by increasing the aspect ratio or growth density of the emitters. The results show that the threshold field of the B/LaB 6 branch-like nanoheterojunctions is 21.6 V/μm (@1 mA/cm2) and their maximum field current density can reach 4.8 mA/cm2 (at 27.5 V/μm). It is suggested a novel Ohmic-contact LaB 6 nanoheterojunction to promote their rapid applications in FE area in future.

Boron is a narrow-bandgap (1.56 eV) semiconductor with high melting-point, low-density, large Young's modulus and very high refractive index (3.03) close to silicon. Therefore, boron nanostructures is expected to possess strong visible-light scattering properties. However, photonic and optoelectronic properties of the boron nanostructures are seldom studied until now. In this paper, we have successfully prepared single-crystalline boron nanowire (BNW) arrays with high-density on Si substrate. All the BNWs are found to possess strong light-scattering behaviors in the visible regime. Most of all, the scattered light is found to polarize along the longitudinal direction of the nanowire. They also have excellent second-harmonic generation (SHG) properties under ultrafast laser irradiation. Further optoelectronic measurements show that an individual BNW device exhibits notable photocurrent responses in the visible-light range at ambient conditions, which can be attributed to the strong coupling effect between individual BNW and the visible light. The maximum photoresponsivity of an individual BNW can reach up to 12.12 A W-1 at a voltage of 10 V, and the response time is only 18 ms. Therefore, it unveils that the BNWs have a promising future in visible-light communications and detections.

WO2 nanowires have great potential as cold cathode materials because they exhibit excellent field-emission properties in terms of their low work function and high conductivity. Considering the requirements of the practical applications in large-area cold-cathode devices, such as X-ray source and panel display, these nanostructures are desired to be fabricated on glass substrate and integrated into devices. It is best known that the studies on WO2 nanowire cold cathode arrays grown on glass-substrate are absent so far, which remains a challenge for the researchers. In the current study, procedures for fabrication of WO2 nanowire cold cathode arrays, which consist of 22000 separated patterns on 1.2 in. glass wafer are developed. It is found that the turn-on and threshold field of the nanowire arrays are, respectively, 6.6 and 9.3 V µm−1. In addition, the performance of the cold cathode arrays is strongly affected by the distribution of the nanowire density as well as the thickness of Al electrode. By modifying the fabrication techniques, over 82% patterns can contribute to the emission, whereby a maximum current density can reach 1.89 mA cm−2. Such a value can fulfill the basic requirement of the large-area cold cathode devices. The research can pave the way for fabrication of high-performance cold cathode devices using glass-substrates.