Work function characterization of directionally solidified LaB6–VB2 eutectic

Abstract

With its low work function and high mechanical strength, the LaB/VB eutectic system is an interesting candidate for high performance thermionic emitters. For the development of device applications, it is important to understand the origin, value, and spatial distribution of the work function in this system. Here we combine thermal emission electron microscopy and low energy electron microscopy with Auger electron spectroscopy and physical vapor deposition of the constituent elements to explore physical and chemical conditions governing the work function of these surfaces. Our results include the observation that work function is lower (and emission intensity is higher) on VB inclusions than on the LaB matrix. We also observe that the deposition of atomic monolayer doses of vanadium results in surprisingly significant lowering of the work function with values as low as 1.1eV.

Hydrogenated Silicon Nanoclusters with a Permanent Electric Dipole Moment for the Controlled Assembly of Silicon-Based Nanostructures

“…One rather efficient method regrettably involves the incorporation of extremely toxic, volatile, and expensive transition metals. 45 Very recently, light-induced WF modulations have been reported; 46 unluckily, it only concerns expensive noble metals that intrinsically possess some of the highest known WF in their elemental form. It is well known that the presence of molecular entities with a permanent dipole moment, as for instance, organic self-assembled monolayers (SAMs), can modify the WF of their substrate material; i.e., the energy necessary for the extraction of electrons can either be increased or decreased dependent on the spatial orientation of the dipole moments.…”

Quantifying work function differences using low-energy electron microscopy: The case of mixed-terminated strontium titanate

“…(b) The experimental offset in landing energy and defocus can be found by calculating the SSR for various d off and E off using Eq. (5). (c) Cut through the SSR landscape in (b) along the d off = 2 µm line.…”

“…It is therefore of great technological relevance for photocathodes, thermionic emission and band alignment in semiconductor devices such as high-k transistors or solar cells [2]. Many materials can exhibit diverse surface reconstructions or terminations with different Φ depending on their treatment and often exhibit domains of different WF on the surface [3][4][5][6]. To understand those materials and to utilize them to their full potential, it is thus necessary to quantify local WF differences ∆Φ with high lateral resolution.…”

Microstructure of mayenite 12CaO·7Al2O3 and electron emission characteristics

“…This method has been exploited to create work function maps for low energy electron microscopy (LEEM) and photoemission electron microscopy (PEEM). [21][22][23] where J is the current density, A is the Richardson constant, k is the Boltzmann constant, T is temperature, and φ is the material's work function. In the absence of field-induced electron emission, forward bias configuration resulting in an electric field of 0.5 V/µm was used to extract all hot electrons.…”