Far-infrared emission from Si-MOSFET’s on high-index surfaces

Voltage-tunable far-infrared emission was observed from n-channel Si-MOSFET’s on high-index surfaces. The emission results from radiative decay of electronic excitations across a minigap in the ground-state subband of the channel. We have observed emission of 10−9 W at 4.4 meV with a linewidth of ∼1 meV. Our results indicate that a voltage-tunable monochromatic source of several times 10−7 W and tuning from ∼1 to ∼20 meV is attainable.