Selective thermal radiation at longitudinal optical phonon energy under geometric condition of metal-semiconductor mesa stripe structures

Abstract

Selective thermal emission at approximately 284 cm−1 with a line width of 13 cm–1 at 628 K is obtained by heating the Au-GaAs mesa-type line and space structures. This emission demonstrates a characteristic polar radiation distribution of electric dipoles and a wavelength independent of the structure size or the direction of emission; thus, it is ascribed to thermally generated electric dipoles resonating with the longitudinal optical phonon energy. This dipole is formed by the interface polarization charges of metal-GaAs-metal stripes. These distinct features are different from the radiation properties of interface phonon polaritons or electronic systems such as intersubband transitions of quantum wells. It is estimated that the mesa height and GaAs space width ranging from hundreds of nanometers to several micrometers provide high generation efficiency of electric dipoles and resultant radiation at high temperatures.