Temperature effects on gated silicon field emission array performance

Silicon field emitter arrays (Si FEAs) are being explored as an electron source for vacuum channel transistors for high temperature electronics. Arrays of 1000 × 1000 silicon tip based gated field emitters were studied by measuring their electrical characteristics up to 40 V of DC gate bias with a 1.3 mA emission current at different temperatures from 25 to 400 °C. At ∼350 °C, residual gas analyzer measurements show that water desorption and carbon dioxide partial pressures increase significantly, the gate to emitter leakage current decreases by more than ten times, and the collector current increases by more than ten times. These improvements remained after heat-treatment but were then lost once the device was exposed to the atmosphere for several days. The improvements could be recovered upon additional baking suggesting that adsorbates (primarily water) on the surface affected field emission and surface leakage. It was also found that after heat-treatment, the electrical characteristics of the devices exhibited <3% variation in collector current at 40 V, which (without exposure to the atmosphere) can be termed as a weak temperature dependence. These results suggest that Si FEAs could be viable as a high temperature transistor.