Electrical Generation of Spontaneous Optical Emission in Electrically Modulated Two-Dimensional Electron Gases at Low-Temperatures

Abstract

A detailed theoretical study is presented for spontaneous optical emission from a two-dimensional electron gas (2DEG) in the presence of a unidirectional spatially periodic modulation at low temperatures. The momentum- and energy-balance equations for electron–photon interactions in the device system are solved self-consistently using the Boltzmann equation, from which we can obtain the frequency and the intensity of the electromagnetic radiation generated. The results obtained indicate that: (1) in an electrically modulated 2DEG at low temperatures, a strong electromagnetic radiation emission up to W/cm2 can be generated by applying a small d.c. electric field; (2) the radiation emission is generated indirectly in the occupied subbands through electronic transitions around the Fermi level; (3) the frequency of the radiation generated is at about 0.1 THz; (4) in the low frequency regime, spontaneous multiphoton emissions can be observed; and (5) this type of optical emission depends strongly on the sample parameters such as the electron density of the 2DEG and the modulation length.