Deposition of nanocrystalline ZnO thin films on p-Si by novel galvanic method and application of the heterojunction as methane sensor

Nanocrystalline Thin Film Gas Sensors

“…Of these the Semiconductor gas sensor is of our particular interest due to their low cost, low power consumption, miniaturization prospect, and robustness [2,4,5]. The challenges for these type of sensors lie in selectivity and characteristics drift, its performance can be greatly improved by techniques such as sensitization and application of nanostructured materials [6,[9][10][11][12].…”

The Effect of Catalytic Metal Contact on Methane Sensing Performance of Nanoporous ZnO -Si Heterojunction

“…The response magnitude in terms of the forward bias current of the sensor is calculated as [4] Where I g is the current in the test gas and I a is the current in air (in pure N 2 in our case). Voltage (V) S1 without gas S1 with gas S2 without gas S2 with gas S3 without gas S3 with gas Table (1) and figure (7) shows the values and bar diagram of the response magnitude (RM), response time(RST) and recovery time(RCT) of the sensor at their respective operating temperature for three different methane concentrations Table 1.…”

“…ZnO is an n-type II-VI compound semiconductor having a wide band gap (~3.3eV), which makes good heterojunction [4] with p-type silicon (Eg~1.1Ev). These heterostructures are very effective in gas sensing applications [5].…”

“…Bhattacharyya et. al [4] investigated ZnO-Si based methane sensor which was based on galvanically deposited ZnO thin film and suffers from the problem of longer response time probably due to the non-porous compact structure of the sensing film. In this report we present ZnO-Si heterojunction sensors for methane detection based on sol-gel grown nanoporous ZnO sensing layer.…”

“…The impact of Pd-Ag catalytic contact has been reported to improve the sensing performance of such sol-gel grown ZnO-p-Si heterojunction sensors through the mechanism of barrier modulation [24,25]. In earlier reports Pd-Ag (26%) alloy were used to fabricate the catalytic contacts [4,12,[21][22][23] but in this report we investigated a different composition Pd-Ag (70%) alloy to envisage its impact on the sensor characteristics. In order to understand the impact of the (Pd-Ag)-ZnO junction in particular we have explored the impact of variation of contact material on the ZnO side of our device as well as the Si side.…”