Continuously Voltage-Tunable Line Absorption in Surface Quantization

Abstract

Photoconductance response due to optical transitions induced by 44.3-meV laser radiation between surface subbands in the inversion layer on a (001) surface of $p$-type silicon is reported. The negative response indicates decreased mobility of electrons in the excited states. Magnetic fields normal to the surface accentuate the response for certain levels because of parallel-motion band mixing. These measurements are the first to demonstrate the large voltage tunability inherent in this electronic energy level system.