The Dependence of FEED of an Individual SWCNT on Temperature and Electric Field

摘要

Carbon nanotubes possess a number of unique electronic properties that result from their nanometer dimensions. As a cold cathode electron source the nanotubes show interesting field-emission properties such as low threshold electric field, high current density and long operating lifetime. However, the physical mechanism of field emission is not fully understood yet. Field emission energy distribution (FEED) is an important tool to explore the electronic states of carbon nanotubes. In the present studies the theoretic results of FEED is dependant on calculation methods. Actually the density of state (DOS) of single-walled nanotube (SWCNT) present many separate bands evidently different from that of metallic emitter. Further calculations show that the DOS of SWCNT are chiral and size dependent. Using the chiral and size dependent DOS of SWCNT one can easily get multi-peaks characteristic FEED. Another important feature is that the applied electronic field competes with the temperature. If the temperature is lower than 1000K, at an moderate applied electric field there is almost no emission above Fermi energy. Thus, it is necessary to give an experimental evidence for the dependence of field emission on temperature and applied electric field and to test the theoretic predictions.