[18p-232-1~17] 3.13 Semiconductor optical devices

▲ [18p-232-2] Current leakage suppression in two-well structural THz-QCLs by using asymmetric design

〇WANG LI, TSUNGTSE LIN, KE WANG, HIDEKI HIRAYAMA

Keywords:terahertz, quantum cascade laser

Great efforts have been contributed since the THz-QCLs first realized, its operating temperature, however, is still far away from room-temperature. It is quite significant to further reveal the quantum transport in cascaded MQWs as exactly as possible and find new schemes to increase the devices operating temperature, at least, to be up to the thermoelectric cooling 230K. Three-wells with resonant tunneling at injecting and extracting process and LO phonon depopulation has been achieved the highest operating temperature of 199.5K. In this paper, we study the two-wells structure: first, we discuss the regular two-wells (GaAs/Al_0.33Ga_0.67As) and reveal the current leakage across the non-active high-energy states suppress the gain obtain at high operating temperatuer and then propose an improved design based on it. It can be defined as asymmetric two-well(Al_xGa_1-xAs/AlGaAs),where x is small to avoid serious alloy scattering induced, to suppress the current leakage. Non-equilibrium green’s functionmethod is used and it need to be noted that electron-electron interaction is included.