Fig. 2 Common-emitter sensing properties of the hydrogen
sensing transistor at various temperatures in 0.01%, 0.1%, and 1%
H2/N2.
(898), and 223 (974) at 25℃ (50℃) in 0.01%, 0.1%, and 1%
H2N2, respectively. Sensing base and
collector currents measured for the hydrogen sensing transistor are
shown in Figs. 3b and 3c. It is found that (i)IBN = 1.88×10-3 µA and (ii)IBH is very close IDH . TheIDH,sat saturates at 0.35 µA (2.3 µA) whileIBH,sat does at 0.44 µA (2.7 µA) in 1%
H2/N2 at 25℃ (50℃). Such a bit of
difference is due to the slightly different voltage across the MSM diode
between the EB hydrogen sensor and the hydrogen sensing transistor.
However, ICH,sat is much larger thanIDH,sat and IBH,sat . This
is reasonable since IBH,sat is amplified by the
current amplify transistor. Calculated GBs ,GCs at 25℃ (50℃) in 0.01%, 0.1%, and 1% are
75, 512 (379, 1.66×104), 134, 977
(1.04×103, 2.78×104), and 233,
2.89×104 (941, 3.41×104),
respectively. Experimental results also prove that our HBT and MSM are
successfully used as a current amplifier and EB-hydrogen sensor.