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.