The cat’s whiskers
John W. Orton · Oxford University Press eBooks · 2008
This chapter covers the history of semiconductors to the end of the Second World War, together with their first practical applications as wireless detectors, rectifiers, and microwave radar detectors. It traces the history of semiconductor physics as it developed between the wars, emphasising the importance of the Hall effect as a technique for characterising semiconductor behaviour. Many different materials showed semiconducting properties but poor control of purity made interpretation difficult. The development of the thermionic valve made cat's whisker detectors redundant in wireless sets but the cat's whisker made a comeback as a radar detector in 1940. The associated development of silicon and germanium led to an appreciation of the vital requirement for pure material and finally allowed a clear distinction to be made experimentally between extrinsic and intrinsic conduction. A final section discusses the nature of scientific research in the context of radio.