Influence of the Ratio of Gate Length to Source-Drain Distance on the Sensitivity of the AlGaN/GaN HEMT Based Chemical Sensors and Biosensors

In this paper, the mechanism of the open-gate AlGaN/GaN HEMT based sensors were discussed and the effect of the ratio of gate length (L-G) to source-drain distance (L-SD) on the transconductance (g(m)) of the sensors was investigated. It was shown that the smaller L-G/L-SD of the devices would get a higher maximum g(m) (g(m-max)). However, when the gate voltage (V-G) increased to a certain extent, the g(m) of the larger L-G/L-SD devices would be higher. The experimental results were demonstrated by further theoretical calculation and analysis which is beneficial to enhance the sensitivity of the AlGaN/GaN HEMT based chemical sensors and biosensors by improving the g(m) of them.