Effect of the Doping Level on the Gas Sensitivity of Si p-n Junctions

Authors O.O. Ptashchenko1, F.O. Ptashchenko2, V.R. Gilmutdinova1, O.S. Kyrnychuk1

1I. I. Mechnikov National University of Odessa, 2, Dvoryanska St., 65026 Odesa, Ukraine

2National University "Odesa Maritime Academy", 8, Didrikhsona St., 65029 Odesa, Ukraine

Е-mail aptash@onu.edu.ua
Issue Volume 10, Year 2018, Number 3
Dates Received 26 December 2017; revised manuscript received 06 June 2018; published online 25 June 2018
Citation O.O. Ptashchenko, F.O. Ptashchenko, V.R. Gilmutdinova, O.S. Kyrnychuk, J. Nano- Electron. Phys. 10 No 3, 03022 (2018)
DOI https://doi.org/10.21272/jnep.10(3).03022
PACS Number(s) 07.07.Df, 68.47.Fg
Keywords Silicon (58) , p-n junction (2) , Gas sensor (5) , Ammonia (2) , Sensitivity threshold, Doping level.

The characteristics of Si diffused p-n junctions as water and ammonia vapors sensors are studied over a wide range of the impurity concentration gradient a. It is established that a lowering of the value a from 6·1023 сm – 4 to 5·1019 сm – 4 decreases the sensitivity threshold Pm of the p-n structures to NH3 vapors (i.e. the lowest vapors partial pressure, which can be detected) by two orders, to about 0.5 Pa. This value is much lower than those of silicon meso-porous membranes and silicon nano-wires fabricated from plates with a boron concentration of 1018 сm – 3. The observed sensitivity threshold variation among the studied samples is due to the influence of uncontrolled surface centers. A treatment of the sample  sequentially in HF and water drastically increases the sensitivity threshold, and the exposure in a Na2S solution significantly lowers it.

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