Hydrogen sensor based on Schottky barriers of Pd/GeO2 using a low cost electrochemically deposited thin GeO2 film

Conductometric semi-conducting metal oxide gas sensors have been widely used and investigated in the detection of gases. They have attracted much attention in the field of gas sensing under atmospheric conditions due to their low cost and flexibility in production, simplicity of their use, and large number of detectable gases. One of such materials is (GeO₂) [1]. In this work, we present a method of synthesis of sub micro-sized germanium dioxide (GeO₂) on porous silicon (PS) by electrochemical deposition. An n-type Si (100) wafer was used to fabricate (PS) where PS was electrochemically anodized in HF based electrolyte, at current density of 50 mA/cm² for 30 min. In the mean time pure GeO₂ is produced through hydrolization of GeCl₄ by hydrogen peroxide and then electrochemically deposited on PS. Palladium (Pd) is deposited on the GeO₂ /PS using RF sputtering technique to produce Schottky contact. The grown GeO₂ crystals were characterized using SEM, EDX, (Fig. 1). Corresponding I-V (Fig. 2) characteristics of the Schottky diodes were measured for different flow rates of hydrogen gas. Thermionic emission model was used to analysis I-V data. The barrier height could be seen to increase significantly with hydrogen flow rate. Sensitivity and response time of the sensor will be discussed.