Consider the following statement),Identify the incorrect one.

Various combinations of n-type and p-type semiconductors are used for making electronic components. Diode is a combination of n-type and p-type semiconductors and is used as rectifier. Transistors are made by sandwiching a layer of one type of semiconductor between two layers of the other type of semiconductors. n-p-n and p-n-p type oftransistors are used to detector amplify radio or audio signals.