A hydrogen sensing Pd/InGaP metal-semiconductor (MS) Schottky diode hydrogen sensor

Abstract

An interesting hydrogen sensing Pd/InGaP metal-semiconductor (MS) Schottky diode has been fabricated and studied. Both the steady state and the transient condition of the hydrogen adsorption process are investigated. Even at room temperature, an extremely low hydrogen concentration of 15 ppm H 2 /air can be detected. In addition, the wide operating temperature range of 250 K of the studied Pd/InGaP hydrogen sensor is found. From experimental results, it is shown that the variation of Schottky barrier height increases with the increase of the operating temperature and hydrogen concentration. As the operation temperature is elevated, the water formation effect is also studied in the quasi-equilibrium region under the transient condition.

The electrical characterization and response to hydrogen of Schottky diodes with a resistive metal electrode—rectifying an oversight in Schottky diode investigation

“…Thus, the absolute sensitivity apparently improves towards lower hydrogen concentrations. In an earlier generation of work on Schottky diode hydrogen sensing, a change of ∼10 3 was reported in forward bias current on exposure to 154 ppm H 2 in N 2 ambient [56]; however, one cannot extrapolate from this result to potential ppm sensitivity since the sensitivity is not a linear function of H 2 concentration; indeed, the trend is for decreasing sensitivity with decreasing hydrogen concentration, [27,28,57] in contrast to the dependence reported here. Our current research effort is geared to determining the ultimate hydrogen sensitivity of the device configuration of figure 3 and addressing its variation as a function of hydrogen concentration.…”

Comparative study of hydrogen sensing characteristics of a Pd/GaN Schottky diode in air and N2 atmospheres

“…Hence, the variations of the reverse current for different hydrogen concentrations both in air and N 2 atmospheres are larger than those for the forward current, even at 570 K. Consequently, because of the large Schottky barrier height change, the Pd/GaN Schottky diode shows a considerably high hydrogen detection capability at high temperatures, especially under the reverse biased condition. Clearly, the Pd/GaN Schottky diode exhibits better thermal stability than other reported hydrogen sensors [19][20][21][22][23] and is a good candidate for hydrogen sensing over a wide operating temperature range. This wide temperature operating range is also a key factor in commercial sensor assessment besides the hydrogen detection sensitivity and response time.…”

“…According to the Langmuir isotherm equation, under the steady-state conditions, the coverage of hydrogen at the interface θ i can be expressed as [15,[20][21][22]:…”

Nanocrystalline Metal Oxides for Methane Sensors: Role of Noble Metals

“…The atomic hydrogen diffuses into the metal/metal oxide junction and reduces the catalytic metal work function. The Schottky energy barrier changes due to the reduction of metal work function and this change can be measured by I-V, C-V, or any other electrical mode [14][15][16].…”