| 摘要 |
PURPOSE:To detect a trace of metal at a high accuracy by thermally decomposing arsenic, phosphor, antimony and a compound thereof with a metal oxide semiconductor to form a metal oxide to measure changes in the resistance value of the semiconductor with the accumulation of the metal oxide. CONSTITUTION:A gas sensor 2 is made of a tin oxide semiconductor, for instance, and provided in a container 4 in such a manner as to be heated with a heater. With the suction by a pump 6, a gas to be measured is introduced into the container 4 from a tube 8. Compounds of trace of arsenic, phosphor and antimony, for example, AsH3, PH3 and SbH3 in the gas to be measured are thermally decomposed with a semiconductor sensor 2 heated up to about 350 deg.C to form metal oxides which are accumulated on the semiconductor sensor 2. Changes in the resistance value are measured before and after the accumulation of the metal oxides on the semiconductor sensor 2 to detect these metals. Thus, a trace (for example, 10ppb) of metal can be detected quantitatively by use of a metal oxide semiconductor sensor. |
