Schematic cross section of the studied Pt-oxide- (MOS) high electron mobility transistor (HEMT) hydrogen sensor.
Common-source output current-voltage characteristics of the studied GaAs-based HEMT under different-concentration hydrogen gases at (a) , (b) , (c) , respectively.
(a) Transconductance and drain saturation current as a function of gate-source voltage of the studied device under different-concentration hydrogen gases at . The inset shows the corresponding values of threshold voltage shift and peak transconductance variation. (b) The threshold voltage shift and peak transconductance variation versus temperature under /air gas and at the forward bias of .
Relationship between the drain saturation current sensitivity and hydrogen concentration of the studied device at different temperature.
Inverse threshold voltage shift vs inverse square root of hydrogen partial pressure of the studied GaAs-based HEMT at different temperature.
Logarithmic value of equilibrium constant as a function of inverse absolute temperature of the studied device.
(a) Transient responses of the studied device at the introduction and removal of 14, 98, 980, and /air mixture gases at room temperature. (b) The transient responses of the studied device under /air gas at 30, 72, 112, and . The applied biases are fixed at and .
Transient response properties of the studied device and previously reported AlGaAs-based Schottky diodes under /air gas at .
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