Scanning tunneling microscopy observations of hafnium carbide thin films as a field emission material

Abstract

We have already reported superior characteristics of field emission from hafnium carbide (HfC)-coated Si field emission arrays. To clarify the microscopic feature of HfC films related to electron emission, the topograph and local work function (LWF) of the HfC film deposited on Si(100) substrates are examined in an atomic scale by using scanning tunneling microscopy (STM). From the STM/LWF images of the sputtering-cleaned film, it is revealed that the HfC film consists of grains with about 10 nm in size, and that the surface stoichiometry at the grain boundaries becomes carbon rich due to preferential sputtering after higher energy argon ion sputtering.

Nanometer-scale Distributions of Field Emission Current Measured with Scanning Tunneling Microscopy

“…The cleanliness of the HfC surface is confirmed by Auger spectra. Fig.5 shows the simultaneously obtained STM and LBH images and their line-profiles [12]. From the STM image, the surface consists of grains with the size of about 10 nm.…”

Processing development of 4TaC-HfC and related carbides and borides for extreme environments

“…It is used in coatings for ultrahigh-temperature environments due to its high hardness, excellent wear resistance, good resistance to corrosion, and low thermal conductivity. It is also used in cutting tools, high-temperature shielding, field emitter tips, and arrays [63][64][65][66] HfC has the lowest work function of all transition metal carbides.…”