| 摘要 |
PROBLEM TO BE SOLVED: To achieve a quantum cascade laser capable of operating at a higher temperature and selecting an oscillation wavelength in a wider band, compared with a conventional art.SOLUTION: A quantum cascade laser oscillates in a terahertz band, and many units are laminated between electrodes to which a voltage is applied. Each unit is configured by two wells configured by alternately laminating two kinds of compound semiconductor layers twice. Laser upper and lower levels are not overlapped with each other spatially. With respect to well layers of the compound semiconductor layers, a Froehlich coupling coefficient in coupling between LO phonon and electron is more than a value of GaAs and equal to or less than a value of GaN, and an LO phonon energy is more than a value of GaAs and equal to or less than a value of GaN. The two kinds of compound semiconductor layers are, a GaN layer of the well layer and an AlGaN layer of a barrier layer, or alternatively, an AlP layer of the well layer and a GaP layer of the barrier layer, or alternatively, an AlGaP layer of the well layer and the GaP layer of the barrier layer, for example. |
