Novel electronic design for double-modulation spectroscopy of semiconductor and semiconductor microstructures

The double-modulation reflectance technique has proven to be a powerful cha racterization tool of semiconductors applied in high-background-light-inter ference systems. In this article, we present a novel and inexpensive electr onic-circuit design for implementing the double-modulation measurements usi ng only one lock-in amplifier. The electronic design is fabricated in an ac cessory hardware of modulation spectroscopy which can easily select the dou ble- or single-modulation mode via a manual switch. Detailed design diagram s of the electronic hardware are described. Measurements of some representa tive samples of semiconductors and actual device structures are carried out . Experimental results demonstrated the well-behaved performance of this de sign. (C) 2001 American Institute of Physics.