Investigations on Pd:SnO2/porous silicon structures for sensing LPG and NO2 gas

Abstract

P-type porous silicon (PS) structure has been prepared by anodic electrochemical etching process under optimized conditions. Photoluminescence studies of the PS structure show emission at longer wavelengths (red) for the excitation at 365 nm. Scanning electron microscope investigations of the PS surface confirm the formation of uniform porous structure, and the pore diameter have been estimated as 25 μm. Pd:SnO 2 /PS/p-Si heterojunction with top gold ohmic contact developed by conventional methods has been used as the sensor device. Sensing properties of the device towards liquefied petroleum gas (LPG) and NO 2 gas have been investigated in an indigenously developed sensor test rig. The response and recovery characteristics of the sensor device at different operating temperatures show short response time for LPG. From the studies, maximum sensitivity and optimum operating temperature of the device towards LPG and NO 2 gas sensing has been estimated as 69% at 180°C and 52% at 220°C, respectively. The developed sensor device shows a short response time of 25 and 57 s for sensing LPG and NO 2 gases, respectively.

LPG sensor based on complete inorganic n-Bi2S3-p-CuSCN heterojunction synthesized by a simple chemical route

“…Very few reports are available for the detection of LPG based on the heterojunction. A Pd: SnO 2 /p-type porous Si/p-Si heterojunction was used by Subramanian et al [13] to sense LPG and NO 2 gas at temperatures above 180 • C. Recently, a few reports have emerged for room temperature LPG sensors based on an electrochemically deposited p-polyaniline with n-CdTe deposited by the electrochemical method [14], n-TiO 2 [15] and n-CdS [16] films deposited by the chemical method. Although the gas sensing devices based on organic materials have sensitivity at room temperature, their long response time due to the orderly structure limits their usage [17].…”

In Situ Growth of ZnO inside a Porous Silicon Matrix Obtained by Electrochemical Etching with a Hydrofluoric Acid-Formaldehyde Solution

“…Gravimetry. We used the gravimetric method to obtain the porosity and etching rate of the PS samples with and without ZnO [17]. In Figure 4, we can note a similar porosity behavior for both electrolyte solutions (HF :CH 2 O : ZnO and HF : CH 2 O).…”

“…The porosity and thickness of PS were 50% and 50 μm, respectively. The porosity and thickness were calculated using the equations of the gravimetric method characterization [17,18]. To obtain ZnO/PS, we first prepared the ZnO using hydrated zinc sulfate (Zn(SO 4 )⋅7H 2 O) in a solution (1 mM) (MEYER 97%; Química Suastes, Mexico) and sodium hydroxide (NaOH) (MEYER 97%) in an solution (1 mM).…”

Формирование И Свойства Захороненного Изолирующего Слоя Двуокиси Кремния В Двухслойных Структурах "Пористый Кремний-На-Изоляторе"

“…Структуры на основе пористого кремния легко инте-грируются с электронным обрамлением в кремниевом технологическом цикле и благодаря развитой поверхно-сти могут служить основой для создания композитных структур для химических микро-и наносенсоров [1][2][3][4][5][6][7]. Для использования преимуществ развитой поверхности макропористого слоя в композитных структурах необхо-дима электрическая изоляция этого слоя от проводящей подложки.…”