Stable field emission currents and low fluctuations are important feasibility requirements for the application of materials in field emission devices and displays. The current stability and current fluctuations of field emitted electrons from graphene films are investigated for the periods of 24 and 100 h. The graphene films showed different percentage of variation from the initial current density for different films ranging from 6% to 46% and the standard deviation in the range of 2–6 μA/cm2. The short- and long-term stability and fluctuations of the graphene films are reported and the causes for degradation of the emission current are discussed.
In the ongoing quest for energy production by nonconventional methods, energy conversion by vacuum and solid-state thermionic emission devices is one of the potentially efficient pathways for converting thermal energy directly into electrical power. The realization of practical of thermionic energy conversion devices strongly depends on achieving low work function materials, which is thus far a limiting factor. In an attempt to develop a new low work function thermionic material, this work reports thermionic emission energy distributions ͑TEEDs͒ from nanocrystalline diamond ͑NCD͒ films in the temperature range from 700 to 900°C that reveal a consistent effective work function of 3.3 eV. The NCD films also exhibit emission peaks corresponding to higher work functions as indicated by shifts in their energy position and relative intensity as a function of temperature. These shifts thus appear to be related to instabilities in the NCD's surface chemistry. The analysis of these data yields information on the origin of the low effective work function of NCD.
With increasing demands on device patterning to achieve smaller critical dimensions and pitches for the 5 nm node and beyond, the need for atomic layer etching (ALE) is steadily increasing. In this work, a cyclic fluorocarbon/Ar plasma is successfully used for ALE patterning in a manufacturing scale reactor. Self-limited etching of silicon oxide is observed. The impact of various process parameters on the etch performance is established. The substrate temperature has been shown to play an especially significant role, with lower temperatures leading to higher selectivity and lower etch rates, but worse pattern fidelity. The cyclic ALE approach established with this work is shown to have great potential for small scale device patterning, showing self-limited etching, improved uniformity and resist mask performance.
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