Doping influence on microwave detection by metal–porous silicon contacts

We present the study of voltage signal rise across both additionally doped and undoped porous silicon diode sensors exposed to microwave radiation. The doped ones exhibit fast, of the nanosecond order, response times, but lower voltage–power responsivity values as compared to similar diodes but containing no porous layer. Insertion of porous surface layer into the undoped samples can significantly enhance their responsivity, however, they demonstrate much slower, of the order of tens of microseconds, response to microwave-modulating pulse. Microwave radiation induces voltage signals of opposite polarity in different types of the porous samples. Models all based mainly on hot carrier effects are exploited to explain the experimental results. Possible aspects of application are discussed as well.